| ZIP Codes: | 28 ZIP Codes (18 Standard, 8 PO Box, 2 Unique) [See All] |
| Area Codes: | 404 / 470 / 678 / 770 / 943 |
| Timezone: | Eastern (GMT -05:00) |
| Local Time: | 2:11:42 PM |
| Population: | 777,758 [See All] |
| FIPS: | 13067 |
| CBSA: | Atlanta-Sandy Springs-Roswell, GA |
| Land Area: | 358 sq mi |
| Water Area: | 5 sq mi |
| Coordinates: | 33.9262, -84.5511 |
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777,758 residents live across 28 ZIPs covering 358 sq mi, served by 9 distinct USPS-recognized cities.
Population moved from 707,392 to 777,758 from 2014 to 2024 — a +9.9% change. 15 ZIPs gained residents, 2 lost.
The county's wealthiest ZIP 30068 (Marietta, $150,101 median) and poorest ZIP 30168 (Austell, $64,059) are 15.5 miles apart — a 2.3× income gap across local geography.
Median home values vary 2.5× across this county — from $241,700 in 30168 (Austell) to $599,400 in 30068 (Marietta).
Density varies 3× across the county — from 1,377 people/sq mi in 30127 (Powder Springs) to 4,253 in 30080 (Smyrna).
Educational attainment ranges from 28.8% bachelor's+ in 30060 (Marietta) to 74.5% in 30068 (Marietta) — the breadth of educational profiles across the area.
Within Georgia, this is the #3 most populous of 161 counties and ranks #7 for median household income with the #48 fastest decade growth .
On the national stage, Cobb County is the #85 most populous US county .
Weighted by population, the typical household earns about $104,595 across the county — reflecting what a typical resident sees, not a simple ZIP average.
50.1% of adults age 25+ hold a bachelor's degree or higher (266,213 of 531,480 reporting). The most-educated ZIPs cluster around Marietta.
18 Standard delivery, 8 PO Box only, 2 single-entity Unique ZIPs serve this county.
| ZIP | City | Type | Population | Median Income | Area (sq mi) | 10-yr Growth |
|---|---|---|---|---|---|---|
| 30127 | Powder Springs | Standard | 71,626 | $110,904 | 52.0 | 18.4% |
| 30101 | Acworth | Standard | 62,593 | $110,774 | 43.0 | 14.0% |
| 30062 | Marietta | Standard | 62,284 | $132,631 | 26.1 | -2.7% |
| 30066 | Marietta | Standard | 61,761 | $116,074 | 27.9 | 16.8% |
| 30144 | Kennesaw | Standard | 59,661 | $88,560 | 22.6 | 12.8% |
| 30080 | Smyrna | Standard | 53,316 | $91,957 | 12.5 | -1.7% |
| 30064 | Marietta | Standard | 52,125 | $122,195 | 30.4 | 14.0% |
| 30067 | Marietta | Standard | 47,271 | $83,568 | 13.7 | 0.2% |
| 30152 | Kennesaw | Standard | 44,977 | $126,578 | 21.9 | 4.5% |
| 30126 | Mableton | Standard | 41,829 | $101,891 | 21.0 | 3.7% |
| 30060 | Marietta | Standard | 38,499 | $67,510 | 12.9 | 7.9% |
| 30008 | Marietta | Standard | 35,547 | $74,877 | 9.4 | 10.9% |
| 30339 | Atlanta | Standard | 35,372 | $103,277 | 10.8 | 76.3% |
| 30068 | Marietta | Standard | 33,882 | $150,101 | 14.8 | 4.6% |
| 30082 | Smyrna | Standard | 27,296 | $120,372 | 10.6 | 4.4% |
| 30168 | Austell | Standard | 26,612 | $64,059 | 11.9 | 0.9% |
| 30106 | Austell | Standard | 23,107 | $68,881 | 13.4 | 21.3% |
| 30111 | Clarkdale | PO Box | 0 | — | 0.1 | — |
| 30090 | Marietta | Standard | 0 | — | 0.0 | — |
| 30061 | Marietta | PO Box | — | — | 0.0 | — |
| 30007 | Marietta | PO Box | — | — | 0.0 | — |
| 30160 | Kennesaw | PO Box | — | — | 0.0 | — |
| 30156 | Kennesaw | PO Box | — | — | 0.0 | — |
| 30081 | Smyrna | PO Box | — | — | 0.0 | — |
| 30006 | Marietta | PO Box | — | — | 0.0 | — |
| 30065 | Marietta | PO Box | — | — | 0.0 | — |
| 30069 | Marietta | Unique | — | — | 3.1 | — |
| 30063 | Marietta | Unique | — | — | 0.0 | — |