Population Density by State: 2020 Census Rankings and Trends

Population density is one of the most revealing ways to understand how people are distributed across the United States. The 2020 Census found that the national average density reached 93.8 people per square mile, up from 87.4 in 2010. Yet that single number hides enormous variation: New Jersey packs 1,263.0 people into each square mile, while Alaska has just 1.3. This article breaks down the official state-by-state density figures, historical changes, and the geographic and economic forces behind them.

Key Numbers

• U.S. average density (2020): 93.8 people per square mile
• Most dense state: New Jersey — 1,263.0 people per square mile
• Least dense state: Alaska — 1.3 people per square mile
• District of Columbia density: 11,280.0 people per square mile
• 10-year density increase: +6.4 people per square mile (2010–2020)
• Total U.S. resident population (2020): 331,449,281
• States with density below 10: 3 (Alaska, Wyoming, Montana)
• Alabama density rank: 29th at 99.2 people per square mile

Explanation

Population density measures how many people live in a given area, usually expressed as people per square mile of land. It is calculated by dividing a state’s total resident population by its land area in square miles. Water bodies such as lakes, rivers, and coastal waters are excluded from the land area, which prevents large water surfaces from artificially lowering density figures.

The United States as a whole is relatively sparsely populated compared with many European and Asian countries, but the national average conceals sharp regional contrasts. The Northeast and Mid-Atlantic states, along with parts of the Pacific coast and Florida, have densities far above the national average. In contrast, the Mountain West, Great Plains, and Alaska have vast open spaces and very low densities.

These differences reflect centuries of settlement patterns, economic development, climate, and physical geography. Coastal ports, industrial centers, and fertile farmland attracted dense populations, while arid deserts, high mountains, and cold northern interiors remained thinly settled.

Definition

Population density is the average number of people living per unit of land area. For U.S. states, the Census Bureau reports density as resident population per square mile of land area. It is a simple ratio, but it is a powerful indicator of how crowded or spacious a state feels and how intensely land is used for housing, commerce, and infrastructure.

How the Statistic Is Calculated

The Census Bureau derives population density from two official components: the decennial census resident population and the land area of each state. The resident population includes all people living in the 50 states and the District of Columbia, excluding U.S. territories unless separately noted. Land area is measured in square miles and excludes inland water, coastal water, and the Great Lakes. The formula is:

Population density = Resident population ÷ Land area (square miles)

For example, New Jersey’s 2020 resident population of 9,288,994 divided by its land area of about 7,354 square miles yields a density of 1,263.0 people per square mile.

Historical Data

The national population density has risen steadily for more than a century as the U.S. population has grown faster than its land area. The following table shows the official U.S. density at each decennial census from 1910 to 2020.

Over the 110-year period, U.S. population density more than tripled, from 26.0 to 93.8 people per square mile.

10-Year Change

Between the 2010 and 2020 censuses, the national average density increased by 6.4 people per square mile, from 87.4 to 93.8. That represents a 7.3% increase over the decade. The growth was not uniform: states in the South and West generally added population faster than the Northeast and Midwest, but many of those fast-growing states also have large land areas, which moderated their density increases. Meanwhile, already dense states such as New Jersey and Rhode Island continued to see modest but steady density gains.

State Comparison

State densities range from Alaska’s 1.3 people per square mile to New Jersey’s 1,263.0 — a nearly 1,000-fold difference. The densest states are concentrated in the Northeast and Mid-Atlantic, where small land areas combine with large metropolitan populations. The least dense states are in the West and Alaska, where federal lands, mountains, deserts, and cold climates limit settlement.

Florida is a notable exception outside the Northeast, ranking 8th among states with 401.4 people per square mile, driven by coastal urbanization and retirement migration. California, despite its huge population, ranks 11th because its land area is also very large.

Ranking Table

The table below lists the 10 most densely populated states and the 10 least densely populated states based on the 2020 Census. The District of Columbia is excluded from the state ranking because it is a federal district, not a state.

Note: Ranks are among the 50 states only. If the District of Columbia were included, it would rank first with 11,280.0 people per square mile.

Largest States

The largest states by land area tend to have low population densities because their populations are spread over vast territories. Alaska, the largest state, has a density of just 1.3 people per square mile. Texas, the second-largest, has a density of 111.6, which is above the national average but still far below the Northeast. California, the third-largest, has a density of 253.7, reflecting its large coastal metropolitan areas. Montana and New Mexico, also among the largest states, have densities of 7.4 and 17.2, respectively.

Smallest States

By contrast, the smallest states by land area are often the most densely populated. Rhode Island, the smallest state, has a density of 1,061.4 people per square mile. Delaware, Connecticut, New Jersey, and Massachusetts — all among the smallest states — have densities of 508.0, 744.7, 1,263.0, and 901.2, respectively. New Jersey is the fourth-smallest state but the most densely populated, showing how a small land area combined with a large population produces extreme density.

Factors Behind the Trend

Several factors explain the wide variation in state population density. Geography and climate play a major role: mountainous terrain, deserts, and extreme cold limit settlement in the West and Alaska, while temperate coastal plains and river valleys in the East supported early agricultural and industrial development. Economic opportunities also matter — port cities, manufacturing hubs, and financial centers attracted dense populations. Historical settlement patterns from the colonial era concentrated people along the Atlantic seaboard, and later migration to the Sun Belt increased density in states like Florida and Texas. Land ownership and federal lands further reduce usable land in many western states, keeping densities low.

Why It Matters

Population density affects nearly every aspect of public policy and daily life. Dense states require more extensive public transit, housing, and utility networks, while sparse states face higher per-capita costs for roads and services. Density influences political representation, infrastructure planning, environmental impact, and emergency response. It also shapes economic development, as businesses often cluster where population density supports large labor markets and customer bases.

Limitations of the Data

While population density is a useful summary measure, it has important limitations. It is an average that can mask internal variation: a state with large empty areas and a few dense cities may have a moderate density that hides extreme local contrasts. For example, Nevada’s density of 28.6 people per square mile obscures the fact that most residents live in the Las Vegas and Reno metropolitan areas, while much of the state is nearly uninhabited. Density also does not account for land use, zoning, or the vertical dimension of urban development. Finally, the official state density rankings include the District of Columbia and Puerto Rico in some Census tables, which can shift ranks if not carefully interpreted.

Methodology

The data in this article come from the U.S. Census Bureau’s decennial census of population and housing. The 2020 Census counted the resident population of the 50 states, the District of Columbia, and Puerto Rico as of April 1, 2020. Land area figures are based on Census Bureau geographic boundaries. Density rankings 1 to 52 include the District of Columbia and Puerto Rico, but the state rankings presented here exclude those jurisdictions for clarity. Historical density figures are from the Census Bureau’s Historical Population Density Data (1910–2020) table.

Source & Data Date

Primary source: U.S. Census Bureau, 2020 Census — Population Density of the 50 States, the District of Columbia, and Puerto Rico: 1910 to 2020, released April 26, 2021. Historical data are from the Census Bureau’s Historical Population Density Data (1910–2020) table. Additional context is drawn from the Census Bureau’s Population Density page.