Why New Jersey Leads State Population Density Rankings

New Jersey has 9,548,215 residents and 7,355.03 square miles of Gazetteer land area. Dividing those values produces 1,298.2 residents per square mile. Rhode Island and Massachusetts follow at 1,078.0 and 917.1.

California’s density is 252.5 despite its larger population of 39,355,309. Alaska has 1.3 residents per square mile. The denominator, as much as the numerator, determines the order. Water area is not included in these calculations.

Consider a two-state comparison using New Jersey and Wyoming. Their populations sum to 10,136,968, and their land areas sum to 104,443.58 square miles. The correct combined density is 97.1 residents per square mile. The simple average of their two separate densities would be 652.1.

Those two results differ because a simple average gives the small land area and the large land area equal weight. For a non-overlapping region, add the populations and compatible land areas first, then divide. This is equivalent to weighting the separate densities by their land areas; it is not equivalent to weighting them by population.

A state includes many types of land and settlement. Its geographic average does not say how densely residents live in their own neighborhoods. A compact urban municipality, an entire county, a Census urban area and a metropolitan statistical area all have different boundaries. Their densities should be named according to the actual unit measured.

DC is particularly relevant to state comparisons: it is a federal district, not a state. It appears in the state/DC directory but is excluded from the 50-state density ranking. Adding it to a “state” ranking without labeling the universe would change the meaning of the result.

Use the July 1, 2025 PEP resident population and join 2025 Gazetteer ALAND by the official state code. ALAND is supplied in square meters; divide by 2,589,988.110336 to convert to square miles. Divide the integer population by the unrounded converted area, and only then round the displayed density.

A code must retain its leading zero. An unmatched area should remain unavailable rather than be replaced with a guessed denominator. The linked ranking sorts unrounded values, even when the rounded display makes neighboring records look close. The interactive chart below compares population growth, not density change; the land-area calculation in the table is fixed to 2025.