San Juan Municipio area

Population and density of San Juan Municipio

The Census Bureau estimates that 329,737 people lived in San Juan Municipio on July 1, 2025. That ranks #228 of 3,222 county equivalents nationally and #1 of 78 in Puerto Rico. Since the April 1, 2020 estimates base of 342,263, the population has declined by 12,526 (−3.7%), compared with −3.1% for Puerto Rico as a whole.

With 47.9 square miles of land, that is 6,883 people per square mile (2,658 per km²), placing San Juan Municipio #16 nationally for density and #1 in Puerto Rico. The median county equivalent has 47 people per square mile; the Puerto Rico median is 754. Put another way, there are about 0.093 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 San Juan Municipio

Puerto Rico has no incorporated places below the municipio: San Juan Municipio is itself the local government. The Census Bureau describes the settlements inside it, such as zonas urbanas and comunidades, as statistical places, and publishes no separate annual estimates for them.

Metropolitan area

San Juan Municipio is a central county of the San Juan-Bayamón-Caguas, PR Metropolitan Statistical Area. Its 40 county equivalents have 2,024,195 residents on 1,437.8 square miles of land; San Juan Municipio accounts for 3.3% of the land and 16.3% of the residents. By combined land it ranks #229 of 393 metropolitan areas, and #36 by population. It belongs to the San Juan-Bayamón, PR Combined Statistical Area.

ZIP codes

21 ZIP Code Tabulation Areas have land in San Juan Municipio; 17 of them have most of their land inside the county, and the others mainly cover neighboring areas.

007250090100906009070090900911009120091300915009170091800920009210092300924009250092600927009660096900976

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 San Juan Municipio

San Juan Municipio shares a land border with 5 county equivalents. It has more land than 4 of them. The largest neighbor is Caguas Municipio (58.6 mi²) and the smallest is Trujillo Alto Municipio (20.7 mi²). Together with its neighbors, San Juan Municipio forms a block of 230.3 mi² of land, of which it holds 20.8%.

How big is San Juan Municipio compared with U.S. states?

San Juan Municipio has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 22 times as much. Puerto Rico’s county land could hold about 71 areas the size of San Juan Municipio.

Another way to picture it: the same land area would fill a square about 6.92 miles (11.1 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 San Juan Municipio?

San Juan Municipio has more land than 90 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 San Juan Municipio at #3,123 nationally by total area, 9 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.

Its water share is 37.8%, compared with a national county-equivalent median of 1.2% — 36.6 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 San Juan Municipio 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.