| City: | Knightsen, California |
| County: | Contra Costa County |
| Timezone: | Pacific (GMT -08:00) |
| Local Time: | 9:52:37 AM |
| Population: | 420 [See All] |
| Area Code: | 925 |
| Classification: | PO Box |
| Coordinates: | 37.9774, -121.6442 |
| Land Area: | 2.311 sq mi |
| Quick Link: |
Knightsen is a small unincorporated community in eastern Contra Costa County, California, sitting at the edge of the Sacramento-San Joaquin River Delta. With just 420 residents and 146 households spread across 0.31 square miles, it's one of the most compact ZIP codes in the eastern Bay Area. Despite its small size, the Knightsen post office maintains 330 PO Boxes, serving more than twice as many boxes as local households.
This 2.26x adoption rate means the post office serves a much wider area than the ZIP boundaries suggest. Surrounding rural properties, farms, and delta communities rely on Knightsen for mail access. This is a PO Box Only Zone. There's no alternative carrier delivery across this territory. Residents and those in surrounding areas must use PO Boxes or General Delivery (which is available here) to receive mail.
Most mail delivery happens through a mixed pattern: 2 city carrier routes serve the compact town center along Knightsen Avenue (which has 61 delivery records, some with unit designators), while 1 rural route covers outlying properties along roads like Delta Road and Quail Trail. The street network includes numbered streets (1st and 2nd) suggesting an old town grid, plus rural connector roads like Eden Plains Road and Sunset Road.
Knightsen's demographics show an affluent commuter community. Median household income is $183,100, well above California averages. Median home values reach $918,100. Nearly half the workforce (45.9%) works from home, the highest rate for any PO Box ZIP in Contra Costa County. This suggests professionals who've chosen delta living while maintaining Bay Area employment. Median age is 43.5 years. Only 2 residents are under 18, indicating few families with children.
The community is predominantly white (277 of 420 residents), with notable diversity: 86 residents identify as some other race, 50 as two or more races, and 46 as Hispanic or Latino. Educational attainment is high, with 33.9% holding bachelor's degrees or higher. There are 12 business establishments employing 55 workers, plus 41 business delivery points, indicating some commercial activity despite the rural character.
Knightsen sits near Brentwood neighborhoods like Sunset Industrial Complex, Hawthorne, and Arroyo Seco Estates, all within 1.5 miles. These nearby communities use different ZIP codes with standard street delivery, highlighting how Knightsen's PO Box classification serves a specific geographic pocket. The post office has operated since before October 2004, when USPS began tracking introduction dates.
All mail must be addressed to PO Boxes or General Delivery:
PO Box [number]
Knightsen, CA 94548or
General Delivery
Knightsen, CA 94548Street names mix old town grid (1st and 2nd Streets) with rural delta roads (Delta Road, Eden Plains Road) and nature references (Quail Trail, Sunset Road).
ZIP Code 94548 has 420 residents and 146 households (average 2.88 persons per household). The median age is 43.5 years, older than the state (37.5) and older than the nation (38.8). The gender split is 50.5% male and 49.5% female, which is slightly higher than the national male share (49.1%). Largest groups are White (66.0%, much higher than the state average of 41.2%) and Hispanic or Latino (40.2%); Hispanic or Latino residents make up 40.2%, which is much higher than the national average (18.7%), and Other / Two or More Races share is much higher than the national average (8.4%).
Explore More:Population Over TimeBy Age & GenderBy RaceBy GenderNativity & Citizenship
| 2020 Population: | 420Source: Census DHC |
| 2024 ACS Population Estimate: | 832Source: Census ACS |
| 2026 ZC Population Estimate: | 0Source: ZIP-Codes.com |
| Population Density: | 181.7 people per sq mile |
| Average Income: | $189,653Source: Census ACS |
| Households: | 146Source: Census DHC |
| Average House Value: | $959,900Source: Census ACS |
| Persons Per Household: | 2.88Source: Census DHC |
| Average Family Size: | 3.47Source: Census ACS |
| Group | 2010 | 2011 | 2102 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Census ACS Population Estimate | -- | 396 | 430 | 338 | 400 | 373 | 379 | 418 | 501 | 377 | 248 | 470 | 598 | 637 | 832 |
| Decennial Census | 412 | -- | -- | -- | -- | -- | -- | -- | -- | -- | 420 | -- | -- | -- | -- |
Median Age: 43.5
Male Median Age: 47
Female Median Age: 42.1
| 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 | 2 | 16 | 16 | 14 | 12 | 13 | 11 | 10 | 11 | 9 | 17 | 23 | 18 | 7 | 12 | 8 | 10 | 3 |
| Female | 9 | 19 | 14 | 20 | 14 | 6 | 3 | 12 | 17 | 11 | 10 | 21 | 16 | 12 | 8 | 10 | 4 | 2 |
| Total | 11 | 35 | 30 | 34 | 26 | 19 | 14 | 22 | 28 | 20 | 27 | 44 | 34 | 19 | 20 | 18 | 14 | 5 |
| White: | 277 | 51.39% |
| Black: | 3 | 0.56% |
| Hispanic:* | 169 | 31.35% |
| Asian: | 3 | 0.56% |
| American Indian: | 0 | 0% |
| Hawaiian: | 1 | 0.19% |
| Other: | 86 | 15.96% |
| Total: | 539 | 100% |
| Gender | Count | % | Median Age |
|---|---|---|---|
| Males: | 212 | 50.48% | 47.0 years |
| Females: | 208 | 49.52% | 42.1 years |
| Total: | 420 | 100% | 43.5 years |
| Native, born in the United States: | 603 | 72.48% |
| Native, born in PR, Island Areas, or abroad: | 0 | 0.00% |
| Foreign born, naturalized U.S. citizen: | 144 | 17.31% |
| Foreign born, not a U.S. citizen: | 85 | 27.52% |
| Total Population: | 832 | 100% |
| Total Native Population: | 603 | 72.48% |
| Total Foreign-born Population: | 229 | 27.52% |
In 2024, the Median household income is $189,653, which is far above the national median ($80,734), is up $127,778 (206.5%) since 2011 and above its 2019 pre-pandemic level by $84,880. Family households earn a median of $189,792 versus $0 for nonfamily households (a difference of $189,792). By gender, male median income is $112,875 and female is $97,461, which is markedly greater than the national female median ($55,274), with a current gap of $15,414 that has widened from 2011 to 2024. The labor-force participation rate is 74.1%, which is considerably higher than the national rate (63.5%). The unemployment rate is 13.5%, which is considerably above the national rate (5.2%). The largest occupation group is Management (40.5%).
Explore More:Income Over TimeHousehold IncomeEmployment StatusBy Occupation
| Income Type | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Median Household Income | $61,875 | $54,375 | $77,750 | $85,000 | $72,250 | $72,059 | $105,329 | $109,453 | $104,773 | $150,492 | $140,417 | $166,597 | $183,100 | $189,653 |
| Median Family Income | $61,042 | $54,063 | $63,295 | $71,750 | $70,333 | $72,059 | $105,329 | $109,609 | $130,972 | $0 | $109,417 | $166,134 | $218,209 | $189,792 |
| Median NonFamily Income | $82,955 | $85,313 | $86,053 | $88,750 | $0 | $0 | $0 | $0 | $0 | $150,682 | $155,486 | $170,694 | $0 | $0 |
| Median Male Income | $58,750 | $39,861 | $36,917 | $37,333 | $0 | $0 | $78,264 | $81,806 | $80,057 | $73,333 | $85,357 | $136,042 | $97,083 | $112,875 |
| Median Female Income | $82,727 | $85,125 | $81,786 | $81,875 | $0 | $0 | $78,542 | $0 | $0 | $151,167 | $0 | $0 | $0 | $97,461 |
| Employed: | 373 | 59.02% |
| Unemployed: | 63 | 9.97% |
| Not In Labor Force: | 196 | 31.01% |
| Total: | 632 | 100% |
| Management, business, science, and arts: | 151 | 40.48% |
| Service: | 107 | 28.69% |
| Sales and Office: | 62 | 16.62% |
| Natural resources, construction, and maintenance: | 20 | 5.36% |
| Production, transportation, and material moving: | 33 | 8.85% |
| Total Civilian Employed Population: | 373 | 100% |
In 2024, the median home value is $959,900, which is much higher than the national median ($332,700), is up $395,900 (70.20%) since 2011 and below its 2019 pre-pandemic level by $102,600. The median gross rent is $0, which is well under the national median ($1,413), is down $723 (100.00%) since 2011 and below its 2019 pre-pandemic level by $1,629. Of occupied housing, owners make up 100.00% (69.50% with a mortgage, 30.50% free-and-clear) and renters 0.00% - making this ZIP Code under national rental averages. The vacancy rate is 0.00%, which is considerably lower than the national rate (10.12%).
Explore More:Compare Home ValueHome Value Over TimeRent & Over TimeHousing Occupancy
| Group | 2011 | 2102 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Median Home Value | $564,000 | $545,100 | $625,000 | $743,200 | $757,600 | $892,900 | $890,600 | $931,400 | $1,062,500 | $886,400 | $817,500 | $1,041,700 | $918,100 | $959,900 |
| Less than $500: | 0 | 0% |
| $500 to $999: | 0 | 0% |
| $1,000 to $1,499: | 0 | 0% |
| $1,500 to $1,999: | 0 | 0% |
| $2,000 to $2,499: | 0 | 0% |
| $2,500 to $2,999: | 0 | 0% |
| $3,000 or more: | 0 | 0% |
| No Rent: | 0 | 0% |
| Total: | 0 | 100% |
| Group | 2011 | 2102 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Median Rent | $723 | $1,125 | $1,350 | $1,350 | $0 | $1,364 | $1,280 | $1,528 | $1,629 | $0 | $0 | $0 | $0 | $0 |
| Owner Occupied (with mortgage): | 180 | 69.50% |
| Owner Occupied (free and clear, no mortgage): | 79 | 30.50% |
| Renter Occupied: | 0 | 0.00% |
| Total Occupied Housing Units: | 259 | 100% |
| Occupied Housing Units: | 259 | 100.00% |
| Vacant Housing Units (not graphed): | 0 | 0.00% |
| Total Housing Units: | 259 | 100% |
| Single-Family Units: | 225 | 86.87% |
| Multi-Family Units: | 0 | 0.00% |
| Other Units: | 34 | 13.13% |
| Total Housing Units: | 259 | 100% |
In 2024, 22.30% of adults (25+) have a bachelor's degree or higher, which is comparable to the national rate (35.70%). High school or higher is 83.40%, which is comparable to the national rate (89.60%). The uninsured rate is 17.50%, which is comparable to the national rate (8.40%). The share of people in poverty is 0.00%, which is comparable to the national rate (8.80%), and below its 2019 pre-pandemic level by 7.00 percentage points. Poverty has been broadly stable, which may reflect structural barriers or offsetting gains and setbacks. Among residents ages 3+, the largest enrollment group is elementary (35.98%). College enrollment is 34.76%, which is comparable to the national rate (26.70%), meaning the community mirrors broader higher-education participation.
Explore More:Educational AttainmentHealth InsurancePoverty Over TimeSchool Enrollment
| Less than 9th grade: | 94 | 16.64% |
| 9th to 12th grade, no diploma: | 0 | 0.00% |
| High school graduate (includes equivalency): | 151 | 26.73% |
| Some college, no degree: | 128 | 22.65% |
| Associate's degree: | 66 | 11.68% |
| Bachelor's degree: | 41 | 7.26% |
| Graduate or professional degree: | 85 | 15.04% |
| Total: | 565 | 100% |
| High school or higher: | 471 | 83.36% |
| Bachelor's degree or higher: | 126 | 22.30% |
| Private Insurance: | 576 | 59.26% |
| Public Insurance: | 256 | 26.34% |
| No Insurance: | 140 | 14.40% |
| Total: | 972 | 100% |
| Has Health Insurance: | 832 | 85.60% |
| Group | 2011 | 2102 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % of People in Poverty | 0.0% | 28.3% | 35.6% | 25.6% | 27.9% | 27.1% | 4.6% | 4.3% | 7.0% | 0.0% | 0.0% | 0.0% | 0.0% | 0.0% |
Note: Counts of Families & People in poverty are not published at the ZIP Code level due to small sample sizes. Percentages shown are survey estimates from the American Community Survey (ACS). They may differ from official poverty statistics. The U.S. Census Bureau defines poverty status by comparing a family's or individual's total income with federal poverty thresholds that vary by family size and composition.
| Nursery School, Preschool: | 10 | 6.10% |
| Kindergarten: | 38 | 23.17% |
| Elementary school (grades 1-8): | 59 | 35.98% |
| High school (grades 9-12): | 0 | 0.00% |
| College or graduate school: | 57 | 34.76% |
| Total: | 164 | 100% |
| Early Childhood: | 48 | 29.27% |
| K-12 (Primary & Secondary School): | 97 | 59.15% |
ZIP Code 94548 supports both business and residential activity. According to the Business Census (2024), there are 10 business establishments, employing about 60 people with an annual payroll of $2,528,000.
| # Residential Mailboxes: | 0Source: USPS |
| # Business Mailboxes: | 0Source: USPS |
| Total Delivery Receptacles: | 2,498Source: USPS |
| Single Family Delivery Units: | 0Source: USPS |
| Multi Family Delivery Units: | 0Source: USPS |
| # of Businesses: | 10Source: CBP |
| 1st Quarter Payroll: | $586,000Source: CBP |
| Annual Payroll: | $2,528,000Source: CBP |
| # of Employees: | 60Source: CBP |
ZIP Code 94548 is located in Contra Costa County, California, within the San Francisco-Oakland-Fremont, CA Metropolitan Statistical Area (CBSA 41860) and California's 10th Congressional District. This Metro area has a population of 4,335,391 people, about 0.01% of whom live in ZIP Code 94548, and is subdivided into the Oakland-Fremont-Berkeley, CA division. It covers 2.311 sq mi of land and a water area of 0.085 sq mi.
| CBSA Name: | San Francisco-Oakland-Fremont, CASource: Census |
| CBSA Number: | 41860Source: Census |
| CBSA Type: | MetroSource: Census |
| CBSA Division: | Oakland-Fremont-Berkeley, CA (CBSA Div 36084)Source: Census |
| CBSA Population: | 4,335,391Source: Census |
| MSA: | San Francisco-Oakland-San Jose, CA CMSASource: Census |
| Land Area: | 2.311 sq miSource: Census |
| Water Area: | 0.085 sq miSource: Census |
| Congressional District: | 10Source: USPS |
| Congressional Land Area: | 1818.79 sq miSource: Census |
| PMSA: | Oakland, CA PMSASource: Census |
| Intro Date: | < 2004-10Source: ZIP-Codes.com |
| Place FIPS Code: | 0638772Source: Census |
| Place Name: | Knightsen CDP; CaliforniaSource: Census |
ZIP Code 94548 is in the Knightsen Elementary School District, which serves grades Kindergarten thru 8th. There are 1 public school(s) in this ZIP Code, and we have located 3 private school(s). It also has 6 colleges, universities or post secondary education institutions nearby which would be a short commute to.
Our sources include trusted federal and licensed data from the United States Postal Service, U.S. Census Bureau, U.S. Geological Survey, Centers for Medicare & Medicaid Services, and the National Center for Education Statistics, along with proprietary datasets created by ZIP-Codes.com. Data last updated on February 1, 2026.