Data Last Updated: May 1, 2025

ZIP Code 52231 in Harper, IA

City: The City name that the USPS assigned as primary for this ZIP Code.	Harper, Iowa
County: ZIP Code 52231 is located in 1 County.	Keokuk County
Timezone: The Time Zone(s) covered. There are 7 standard time zones which are, from west to east: Hawaii-Aleutian, Alaska, Pacific, Mountain, Central, Eastern, Atlantic. Also included in U.S. Territories are Samoa, Guam and Palau.	Central (GMT -06:00)
Local Time: The current local time for each timezone. If more than 1 time zone for this area, all local times will be shown. Area codes can cross timezones, so more than 1 may be shown.	9:45:21 PM
Population: The number of people living in the 52231 ZIP Code from the U.S. Census 2020. Included are U.S. Citizens, permanent residents, temporary migrants, and undocumented individuals. The total represents people who live here, not just those present while the Census was being completed.	316 [See All]
Area Code: There are 0 Area Codes assigned to this ZIP Code.	641
Classification: This type is assigned to ZIP Codes which primarily use street delivery to mailboxes. Standard (Non-Unique) types can include PO Boxes, but this will be the minority use.	Standard [Normal Street Delivery]
Coordinates: The latitude/longitude centroid coordinates for this area.	41.3578, -92.0727
Land Area: The approximate amount of land area covered by ZIP Code 52231 in square miles.	34.521 sq mi
Quick Link: Copy the direct link to this page and use anywhere you like!	https://www.zip-codes.com/zip-code/52231/zip-code-52231.asp

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ZIP Code 52231 Demographic Profile

Population & People

Total Population

316

More | See by Race

Income

Median Household Income

$69,545

See Chart

Housing

Total Housing Units

146

Health

Without Healthcare Coverage

0.38%

See Chart

Business & Economy

Total Businesses

Families

Total Households

139

Employment

Employment Rate

68.55%

See Chart

Education

Bachelor's Degree or Higher

16.13%

Important ZIP Code 52231 Information

ZIP Code 52231 is located in the city of Harper, Iowa and covers 34.521 square miles of land area. It is also located within Keokuk County.

According to the 2020 U.S. Census, there are 316 people in 139 households. ZIP-Codes.com estimates that the current population is 329. It has a population density of 9.2 people per square mile.

52231 is classified as a "non-unique", also known as a Standard ZIP Code. Its primary purpose is for normal street, apartment, and business mailbox delivery. Carriers will deliver mail to this region through vehicles, walking routes, and other means. It may also have PO Boxes located at the USPS facility.

52231 is in the Central (GMT -06:00) timezone and does observe daylight saving time. It only has the 641 Area Code providing telephone service.

The Map above shows the boundaries and what geography it covers. More Demographics are available below, including charts for population by race, population by gender, population over time, house value, income over time, and much more. Local Public, Private, and Post Secondary Schools shows which schools are nearby.

52231 is in a locale that is not assigned to a Core-Based Statistical Area (CBSA). CBSA's are geographic regions with significant populations of 10,000+ and adjacent communities which integrate with the core area.

The 52231 ZIP Code is home to 5 businesses, employing 34 people. That is an average of 6.8 employees per business. Annual payroll for these businesses is $1,951,000. See Other Demographics.

ZIP Code 52231 Demographics

Current Population: This field gives the estimated household population for this ZIP Code for February, 2025. This is derived from known delivery information, household occupancy rates, household size, and more to come up with an accurate estimation for the current population. IMPORTANT: This does not include population totals for persons in nursing homes, correctional facilities, or other institutions. This is an estimation of the household population based on US Postal Service delivery information.	329
2020 Population: Total Population from the 2020 Census. This reflects the exact population of the geographic region at that point in time, not future estimates, regardless of citizenship or immigration status. It is intended to count all persons living within the geographic area, not just those present on the day of the census.	316
Population Density: Population density is a measurement of population per unit of land area. In this case, the number is expressed in people per square mile.	9.2 people per square mile
Average Income: The Median Household income from the Census American Community Survey.	$69,545

Households: Total estimated amount of households based on Census 2020 ZCTA.	139
Average House Value: The Median house value from the Census American Community Survey.	$228,700
Persons Per Household: Avg number of individuals per household. The avg number of individuals per household are not projected to the future, they are actual Census 2020 numbers.	2.27
Average Family Size: Average Family Size is calculated by dividing the number of people in a Family Household by the number of Family Households. The U.S. Census Bureau defines family households as households consisting of two or more individuals who are related by birth, marriage, or adoption. They also may include other unrelated people. Non-family households consist of people who live alone or who share their residence with unrelated individuals. The Avg Family Size only looks at the households classified as Family Households. This value from the U.S. Census ACS (American Community Survey) and is updated yearly.	2.41

Pie Chart & Table Comparison Chart

Population by Race

White: The number of individuals who selected White as their race from the 2020 Census for this geographic area. The numbers for the White Population are not future projections. On the 2020 U.S. Census questionnaire, people were asked to check all races which applied to them, including White. This includes all who selected White/Caucasian in their response, even if they selected another race as well.	304	98.38%
Black: The number of individuals who selected Black as their race from the 2020 Census for this geographic area. The numbers for the Black Population are not future projections. On the 2020 U.S. Census questionnaire, people were asked to check all races which applied to them, including Black or African American. This includes all who selected Black or African American in their response, even if they selected another race as well.	0	0%
Hispanic: The number of individuals who selected Hispanic from the 2020 Census for this geographic region. On the 2020 U.S. Census questionnaire, people were first asked for their Ethnicity, including if they were from Hispanic, Latino, or Spanish Origin, including Mexican, Mexican American, Chicano, Puerto Rican, Cuban, or other ethnic origin. This includes all who affirmed that they were part of this ethnic origin. Respondents who selected this option were also asked to select a race separately and would be counted once in this number as well as the race they chose. From the U.S. Census definition, Hispanic is an ethnic origin and not a race.	3	0.97%
Asian: The number of individuals who selected Asian as their race from the 2020 Census for this geographic area, not future projections. On the U.S. Census questionnaire, people were asked to check all races which applied to them, including Chinese, Filipino, Asian Indian, Vietnamese, Korean, Japanese, or Other Asian. This includes all who selected one of these options in their response, even if they selected another race as well.	0	0%
American Indian: The number of individuals who selected American Indian or Alaska Native Population as their race from the 2020 Census for this geographic region and not estimates for the future. On the 2020 U.S. Census questionnaire, people were asked to check all races which applied to them, including American Indian and Alaska Native. This includes all who selected American Indian and Alaska Native in their response, even if they selected another race as well.	0	0%
Hawaiian: The number of individuals who selected Hawaiian or Pacific Islander Population as their race from the 2020 Census for this geographic region and are not future projections. On the 2020 U.S. Census questionnaire, people were asked to check all races which applied to them, including Native Hawaiian and Pacific Islander. This includes all who selected either Hawaiian or Pacific Islander in their response, even if they selected another race as well.	0	0%
Other: The number of people for all other races per ZIP code based on Census 2020 Zip Code Tabulation Area. The other race population numbers are not projected to the future, they are actual Census 2020 numbers.	2	0.65%

Pie Chart showing Population by Race: White [304, 98.38%], Black [0, 0%], Hispanic [3, 0.97%], Asian [0, 0%], Hawaiian [0, 0%], American Indian 0, 0%], and Other [2, 0.65%] for ZIP Code 52231 in Harper, IA. Load Chart

Source: U.S. Census Bureau (2020) DHC

Pie Chart & Table Comparison Chart

Gender Breakdown

Males: The # of Males from the 2020 Census. Each respondent self-identified on the survey, as they were asked to indicate their sex assigned at birth. The number of Males is important for healthcare planning, policy making, social research, and economic planning and development.	147	46.52%
Females: The # of Females from the 2020 Census. Each respondent self-identified on the survey, as they were asked to indicate their sex assigned at birth. The number of Females is important for healthcare planning, policy making, social research, and economic planning and development.	169	53.48%
Median Age: The Average Age of all persons from the 2020 Census. Median age is the middle age of the population. Half the population is older than the avg age and half is younger. Median Age can relate how young or old a geographic region is compared to others.		38.3 years
Male Median Age: The Average Age of all Males from the 2020 Census. The Male Median Age is the actual avg from the 2020 Census. Median Age is the avg age of the population. Half of the population is older and the other half is younger. This is self-reported by individuals when asked about their sex at birth.		39.5 years
Female Median Age: The Average Age of all Females from the 2020 Census. The Female Median Age is the actual avg from the 2020 Census. Median Age is the avg age of the population. Half of the population is older and the other half is younger. This is self-reported by individuals when asked about their sex at birth.		38.1 years

Pie Chart showing population of Males [147, 46.52%] vs Females [169, 53.48%] for 52231 in Harper, IA. Load Chart

Source: U.S. Census Bureau (2020) DHC

Population by Age & Gender

Median Age: The Median Age of all people from the 2020 Census. Median age is the middle age of the population. Half the population is older than the average age and half is younger. Median Age can relate how young or old a geographic region is compared to others. 38.3

Male Median Age: The Median Age of all Males from the 2020 Census for this geographic area. The Male Median Age is the actual average from the 2020 Census. Median Age is the average age of the population. Half of the population is older and the other half is younger. This is self-reported by individuals when asked about their sex at birth. 39.5

Female Median Age: The Median Age of all Females from the 2020 Census for this geographic area. The Female Median Age is the actual average from the 2020 Census. Median Age is the average age of the population. Half of the population is older and the other half is younger. This is self-reported by individuals when asked about their sex at birth. 38.1

Line Chart showing the population by Age Group and Gender. One line shows the Total number of people for ZIP 52231 in that age group, another line shows the number of Males for that age group, and the last line shows the number of Females for the given age group. A table also provides the same information below. Load Chart

Source: U.S. Census Bureau (2020) DHC

Group	< 5	5-9	10-14	15-19	20-24	25-29	30-34	35-39	40-44	45-49	50-54	55-59	60-64	65-69	70-74	75-79	80-84	85+
Male	10	7	13	15	7	5	12	5	8	3	12	4	18	16	6	2	2	2
Female	11	22	18	9	6	5	7	19	12	2	5	1	20	13	4	5	3	7
Total	21	29	31	24	13	10	19	24	20	5	17	5	38	29	10	7	5	9

Average Income per Household

Bar Chart showing Average Income per Household and comparing it to the city of Harper, Keokuk County, the State of Iowa, and the United States National Average. Load Chart

Source: U.S. Census 2019-2023 American Community Survey 5-Year Estimates. Table DP03. SELECTED ECONOMIC CHARACTERISTICS

Income Estimate Over Time

Line Chart showing Median Income Estimates from 2011 until 2021 for Median Household Income, Median Family Income, Median Nonfamily Income, Median Male Income, and Median Female Income for the 52231 ZIP Code. A table also provides the same information below. Load Chart

Source: U.S. Census 2011-2023 American Community Survey 5-Year Estimates. DP03. SELECTED ECONOMIC CHARACTERISTICS

Income Type	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020	2021	2022	2023
Median Household Income	$39,554	$39,875	$64,583	$65,536	$63,594	$60,000	$61,429	$64,531	$57,396	$63,125	$64,375	$85,769	$69,545
Median Family Income	$64,773	$64,712	$105,104	$98,750	$91,500	$93,438	$85,625	$73,750	$76,250	$102,788	$95,357	$104,500	$110,966
Median NonFamily Income	$30,729	$31,932	$32,656	$31,406	$32,321	$33,750	$34,688	$44,583	$44,583	$44,107	$52,500	$51,250	$36,563
Median Male Income	$36,354	$41,250	$46,250	$46,250	--	$57,500	$46,875	$47,143	$58,500	$39,904	$42,361	$44,784	$47,096
Median Female Income	$35,625	$38,571	$39,792	$45,750	--	$44,583	$45,625	$46,875	$41,250	$41,667	$41,875	$53,750	$36,711

Average House Value

Bar Chart showing Average House Value for the 52231 ZIP Code and comparing it to the city of Harper, Keokuk County, the State of Iowa, and the United States National Average. Load Chart

Source: U.S. Census 2019-2023 American Community Survey 5-Year Estimates. Table DP03. SELECTED ECONOMIC CHARACTERISTICS

Population Estimate Over Time

Line Chart showing Population Estimates from 2011 until 2021 for ZIP Code 52231 with Decennial U.S. Census lines for 2010 and 2020 actual populace. A table also provides the same information. Load Chart

Source: U.S. Census 2011-2023 American Community Survey 5-Year Estimates. DP05. DEMOGRAPHIC AND HOUSING ESTIMATES

Group	2010	2011	2102	2013	2014	2015	2016	2017	2018	2019	2020	2021	2023	2023
Population Estimate	--	283	253	299	254	254	232	189	199	214	310	373	439	497
Decennial Census	328	--	--	--	--	--	--	--	--	--	316	--	--	--

Pie Chart & Table Comparison Chart

Employment Status

Employed: Employed includes all civilians 16 years old and over who were either (1) "at work" -- those who did any work at all during the reference period as paid employees, worked in their own business or profession, worked on their own farm, or worked 15 hours or more as unpaid workers on a family farm or in a family business; or (2) were "with a job but not at work" -- those who did not work during the reference period but had jobs or businesses from which they were temporarily absent due to illness, bad weather, industrial dispute, vacation, or other personal reasons.	231	68.55%
Unemployed: All civilians 16 years old and over are classified as unemployed if they (1) were neither "at work" nor "with a job but not at work" during the reference period, and (2) were actively looking for work during the last 4 weeks, and (3) were available to accept a job. Also included as unemployed are civilians who did not work at all during the reference period, were waiting to be called back to a job from which they had been laid off, and were available for work except for temporary illness.	6	1.78%
Not In Labor Force: Not in labor force includes all people 16 years old and over who are not classified as members of the labor force. This category consists mainly of students, housewives, retired workers, seasonal workers interviewed in an off season who were not looking for work, institutionalized people, and people doing only incidental unpaid family work (less than 15 hours during the reference period).	100	29.67%

Pie Chart showing Employment Status for those Employed, Unemployed, and Not In the Labor Force. A table also provides the same information. Load Chart

Source: U.S. Census 2019-2023 American Community Survey 5-Year Estimates. Table DP03. SELECTED ECONOMIC CHARACTERISTICS

Gross Rent Paid

Less than $500: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.) fuels. This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid under $500 per month.	0	0.00%
$500 to $999: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid between $500 to $999 per month.	24	96.00%
$1,000 to $1,499: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid between $1,000 to $1,499 per month.	1	4.00%
$1,500 to $1,999: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid between $1,500 to $1,999 per month.	0	0.00%
$2,000 to $2,499: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid between $2,000 to $2,499 per month.	0	0.00%
$2,500 to $2,999: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid between $2,500 to $2,999 per month.	0	0.00%
$3,000 or more: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which paid $3,000 or more per month.	0	0.00%
No Rent: Gross rent is the monthly rent plus the estimated average monthly cost of utilities (electricity, gas, water and sewer) and fuels (oil, coal, kerosene, wood, etc.). This shows the number of renter-occupied units paying cash rent (excluding one-family houses on ten or more acres) and percentage which pay no rent per month.	0	0.00%

Pie Chart showing Gross Rent Paid by renters in the 52231 ZIP Code. A table also provides the same information. Load Chart

Source: U.S. Census 2019-2023 American Community Survey 5-Year Estimates. Table Table DP04. SELECTED HOUSING CHARACTERISTICS

Pie Chart & Table Comparison Chart

Health Insurance

Private Insurance: Census Estimate of the Civilian noninstitutionalized people with private health insurance. Private health insurance is a plan provided through an employer or union; a plan purchased by an individual from an insurance company; or TRICARE or other military health coverage.	312	58.65%
Public Insurance: Census Estimate of the Civilian noninstitutionalized people with public health insurance. Public coverage includes the federal programs Medicare, Medicaid and other medical assistance programs, VA and CHAMPVA Health Care; the Children’s Health Insurance Program (CHIP); and individual state health plans. The ACS questionnaire does not specifically ask about these types of coverage, but respondents who indicate these types of coverage are counted as having public coverage.	218	40.98%
No Insurance: Census Estimate of the Civilian noninstitutionalized people with no health insurance of any kind. People whose only health coverage is Indian Health Service are uninsured as IHS is not considered comprehensive coverage.	2	0.38%

Pie Chart showing Civilian noninstitutionalized people with Private, Public, or No Health Insurance coverage for individuals in this geographic area. A table also provides the same data. Load Chart

Source: U.S. Census 2019-2023 American Community Survey 5-Year Estimates. Table DP03. SELECTED ECONOMIC CHARACTERISTICS

Other Demographics

# Residential Mailboxes: The number of active residential delivery mailboxes and centralized units. This excludes PO Boxes and all other contract box types.	145
# Business Mailboxes: The number of active business delivery mailboxes and centralized units. This excludes PO Boxes and all other contract box types.	12
Total Delivery Receptacles: The total number of delivery receptacles. This includes curb side mailboxes, centralized units, PO Boxes, NDCBU, and contract boxes. This for Residential and Business combined.	152
Single Family Delivery Units: Total of single family mail delivery receptacles; generally analogous to homes.	113
Multi Family Delivery Units: Total of multifamily mail delivery receptacles; generally analogous to apartments.	0

# of Businesses: The total number of Business Establishments. Taken from Business Census 2023.	5
1st Quarter Payroll: The total payroll for the first quarter. Taken from Business Census 2023.	$517,000
Annual Payroll: The total annual payroll. Taken from Business Census 2023.	$1,951,000
# of Employees: The total number of employees. Taken from Business Census 2023.	34

52231 ZIP Code Geography & Statistical Areas

CBSA Name: Name of the Core Based Statistical Area . A Core Based Statistical Area is the official term for a functional region based around an urban center of at least 10,000 people, based on standards published by the Office of Management and Budget (OMB) in 2000. These standards are used to replace the definitions of metropolitan areas that were defined in 1990. A CBSA is broken into two sub categories, Metro and Micro, and are detailed in the CBSA Type Field. These are defined by their population densities. To be considered a Micro area, population must be between 10,000 and 50,000. To be considered a Metro area, population must exceed 50,000.	--
CBSA Number: Core Based Statistical Area (replaces old MSA's). A Core Based Statistical Area is the official term for a functional region based around an urban center of at least 10,000 people, based on standards published by the Office of Management and Budget (OMB) in 2000.	--
CBSA Type: Indication of whether a CBSA is Metro (over 50,000 people) or Micro (10,000 - 50,000 people).	--
CBSA Division: Name of the Core Based Statistical Area Division. A metropolitan statistical area containing an urbanized region of at least 2.5 million people can be subdivided into two or more 'metropolitan divisions', provided specified criteria are met. Metropolitan divisions are conceptually similar the primary metropolitan statistical areas (PMSAs) defined under previous standards. This field gives the sub-divided region name	--
CBSA Population: The estimated number of people for the selected CBSA. Source: Table DP-1: Profile of General Population and Housing Characteristics: 2010. 2010 Census Summary File 1.	0
MSA: Metropolitan Statistical Area Description Name. MSA's were replaced by CBSA's in the 90's. We keep the old MSA's in our data because some of our older customers have mapped their data by this information.
Land Area: The approximate amount of land area covered by this ZIP Code in Square Miles.	34.521 sq mi
Water Area: The approximate amount of water area covered by this ZIP Code in Square Miles.	0.044 sq mi

Congressional District: The 119th Congressional District comes from the Census for congressional districts of the 119th Congress. This field shows which districts the ZIP Code belongs to.	01
Congressional Land Area: This field provides the approximate land area covered by the Congressional District for which the ZIP Code belongs to.	12048.84 sq mi
PMSA: Primary Metropolitan Statistical Area. This is the region that the Census Bureau designates as the 'primary' region within a given MSA.
Intro Date: The date this ZIP Code was introduced by the USPS into service. It is in the form of YYYY-MM. In cases where the actual date is unknown, it will be preceded by a < to indicate 'Before this date'.	< 2004-10
Place FIPS Code: FIPS codes, or Federal Information Processing Standards, are numeric codes that uniquely identify geographic areas. The National Institute of Standards and Technology (NIST) assigns FIPS codes. The number of digits in a FIPS code varies depending on the level of geography. This is the 7 digit FIPS Code for the Place that this record covers (if known).	1934545
Place FIPS: FIPS codes, or Federal Information Processing Standards, are numeric codes that uniquely identify geographic areas. The National Institute of Standards and Technology (NIST) assigns FIPS codes. The number of digits in a FIPS code varies depending on the level of geography. This is the name of the FIPS for the Place that this record covers (if known).	Harper city; Iowa

Adjacent & Nearby 52231 ZIP Codes

52591: Sigourney, IA
52335: South English, IA
52248: Keota, IA
52355: Webster, IA
52576: Ollie, IA
52562: Hayesville, IA
52316: North English, IA
52585: Richland, IA
52359: West Chester, IA
50136: Keswick, IA
52356: Wellman, IA
50255: PO BOX
52550: Delta, IA
50268: What Cheer, IA
52308: PO BOX
52568: PO BOX
52580: Packwood, IA
52563: Hedrick, IA
52325: Parnell, IA
52540: Brighton, IA

Next: 52232 52229: Previous

Schools in ZIP Code 52231

We could not locate which school district ZIP Code 52231 belongs to, but we will update this once updated district data is released. There are no public schools nor private schools with a mailing address in the 52231 ZIP Code, but we have located several schools which are nearby. ZIP Code 52231 also has 6 universities, colleges or post secondary education institutions nearby which would be a short commute to.

Keota High School
507 N Ellis St
Keota, IA 52248
District: Keota Community School District (nearby)

Keota Elementary School
505 N. Ellis Street
Keota, IA 52248
District: Keota Community School District (nearby)

Sigourney Jr-Sr High Sch
907 E Pleasant Valley
Sigourney, IA 52591
District: Sigourney Community School District (nearby)

Sigourney Elementary
509 S. Jefferson
Sigourney, IA 52591
District: Sigourney Community School District (nearby)

Tri-County Elementary School
3003 Hwy 22
Thornburg, IA 50255
District: Tri-County Community School District (nearby)

Hillcrest Academy
1421 540th St Sw
Kalona, IA 52247
District: Private School (nearby)

Lutheran Interparish School
804 Ct St
Williamsburg, IA 52361
District: Private School (nearby)

Colleges & Post Secondary Schools near ZIP Code 52231

Shiloh University
6718 Etiwanda Ave.
Rancho Cucamonga, CA 91739
Type: Post Secondary

Maharishi International University
1000 North 4th Street
Fairfield, IA 52557
Type: Post Secondary

Indian Hills Community College
525 Grandview Ave
Ottumwa, IA 52501
Type: Post Secondary

Iowa School Of Beauty-Ottumwa
609 W Second St
Ottumwa, IA 52501
Type: Post Secondary

William Penn University
201 Trueblood Ave
Oskaloosa, IA 52577
Type: Post Secondary

University Of Iowa
101 Jessup Hall
Iowa City, IA 52242-1316
Type: Post Secondary

References

U.S. Postal Service [Last Updated: 5/1/2025], https://www.usps.com
ZIP-Codes.com Internal Data Creation [Last Updated: 5/1/2025], https://www.zip-codes.com
U.S. Geological Survey [Updated as needed], https://www.usgs.gov
U.S. Census [Updated Yearly], https://www.census.gov
U.S. Census American National Standards Institute (ANSI) [Last Updated: 5/1/2025], https://www.census.gov
U.S. Census 2020 [Decennial] [Last Updated: 5/25/2023], https://www.census.gov
Centers for Medicare & Medicaid Services [Updated Yearly], https://www.cms.gov
National Center for Education Statistics [Last Updated: 5/1/2025], https://nces.ed.gov