Onondaga County area

Population and density of Onondaga County

The Census Bureau estimates that 466,584 people lived in Onondaga County on July 1, 2025. That ranks #159 of 3,222 county equivalents nationally and #11 of 62 in New York. Since the April 1, 2020 estimates base of 476,513, the population has declined by 9,929 (−2.1%), compared with −1% for New York as a whole.

With 778.4 square miles of land, that is 599 people per square mile (231 per km²), placing Onondaga County #290 nationally for density and #14 in New York. The median county equivalent has 47 people per square mile; the New York median is 112. Put another way, there are about 1.1 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Onondaga County

Onondaga County is divided into 21 cities and towns. In New York, county subdivisions are local governments, and together they cover all of the county’s land and residents.

The most populous is Syracuse city, with 144,896 residents (31.1% of the county). The largest by land is Pompey town, at 66.4 mi², or 8.5% of the county’s land. Among those with at least 1,000 residents in 2020, Spafford town grew fastest since then (+0.4%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each subdivision inside Onondaga County. Land: 2026 Census Gazetteer. How communities are listed.

Metropolitan area

Onondaga County is a central county of the Syracuse, NY Metropolitan Statistical Area. Its 3 county equivalents have 652,273 residents on 2,384.9 square miles of land; Onondaga County accounts for 32.6% of the land and 71.5% of the residents. By combined land it ranks #138 of 393 metropolitan areas, and #92 by population. It belongs to the Syracuse-Auburn, NY Combined Statistical Area.

ZIP codes

58 ZIP Code Tabulation Areas have land in Onondaga County; 45 of them have most of their land inside the county, and the others mainly cover neighboring areas.

13020130211302713029130301303113035130371303913041130511305213057130601306313066130691307713078130801308213084130881309013104131081311013112131161311913120131221313513138131411315213153131581315913164131661320213203132041320513206132071320813209132101321113212132141321513219132241324413290

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Onondaga County

Onondaga County shares a land border with 4 county equivalents. It has more land than 3 of them. The largest neighbor is Oswego County (951.6 mi²) and the smallest is Cortland County (498.8 mi²). Together with its neighbors, Onondaga County forms a block of 3,575.2 mi² of land, of which it holds 21.8%.

How big is Onondaga County compared with U.S. states?

Onondaga County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.3 times as much. New York’s county land could hold about 61 areas the size of Onondaga County.

Another way to picture it: the same land area would fill a square about 27.9 miles (44.9 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Onondaga County?

Onondaga County has more land than 2,108 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Onondaga County at #1,164 nationally by total area, 50 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 3.4%, compared with a national county-equivalent median of 1.2% — 2.2 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Onondaga County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.