Regions of the United States

The four regions and nine divisions

The Census Bureau groups the states into four regions, and each region into two or three divisions. The Northeast is made up of New England and the Middle Atlantic states; the Midwest of the East and West North Central divisions; the South of the South Atlantic, East South Central and West South Central divisions; and the West of the Mountain and Pacific states. The District of Columbia, which is not a state, counts as part of the South Atlantic.

The Bureau’s stated purpose is to group states that are roughly similar in their history, their population and their economy. The regions and divisions have been used in almost all Census Bureau tables since the early 1900s, and other federal agencies, researchers and businesses use them too. That is the main reason they have barely changed: a century of statistics depends on comparing the same groups of states.

Older than they look

The first regions appeared in the published results of the 1850 census, compiled under James D. B. DeBow, who became Superintendent of the Census in 1853. They split the country into five “great divisions.” Most have since disappeared, but one has not: New England was already the same six states it is today.

The modern system goes back to the 1880s, when Henry Gannett, the Geographer of the Census Office, divided the country into an Atlantic section, the Great Valley of the Mississippi and the West. He split the two eastern sections along a line running roughly east to west, following the Mason-Dixon line and then the Ohio River and the southern boundary of Missouri. His five major divisions became today’s regions, and many of his eleven smaller ones became today’s divisions.

The nine divisions, as they stand now, first appeared in the population report of the 1910 census. In 1950 the Bureau began calling its large units regions rather than sections, and split the old North into the Northeast and the North Central region. Alaska and Hawaii joined the Pacific division with the 1960 census, and in June 1984 the North Central region was renamed the Midwest.

Why Delaware and Maryland count as the South

Gannett’s line explains some of the system’s surprises. Because the boundary follows the Mason-Dixon line, Delaware, Maryland and the District of Columbia fall in the South, along with West Virginia. After the 1950 census, a Commerce Department committee tested the old groupings with modern statistical methods and proposed a new map. It moved Delaware, Maryland and Washington, D.C., into the Middle Atlantic, created a Southwest division of Texas, Oklahoma, Arizona and New Mexico, and put Nevada with the Pacific states. Statistically it was an improvement, but data users did not accept it widely enough, and the Bureau kept the existing regions so that long-running statistics would stay comparable.

How the regions compare

The four regions are very unequal. The South has the most states and the most people, about 133 million in 2025, nearly two in five Americans, and it has grown fastest since 2020, by about 6 percent. Texas and Florida alone account for more than 55 million of its residents. The West covers almost half the country’s area but has less than a quarter of its people; Alaska makes up a third of the region’s area by itself, and the Mountain division is the least densely settled in the country, with about 31 people per square mile.

The Northeast is the smallest region, with less than 5 percent of the land but 17 percent of the people. It is the most densely populated, and its Middle Atlantic division, New York, New Jersey and Pennsylvania, averages about 429 people per square mile. The Midwest sits in the middle on almost every measure: 12 states, about a fifth of the population and a fifth of the area, and slow growth of about 1 percent since 2020.

Other ways to divide the country

The Census map is not the only one. In the 1970s the federal Office of Management and Budget created ten Standard Federal Administrative Regions, based on a survey of state officials; New England is the only region that matches in both systems. Everyday names such as the Pacific Northwest, the Southwest, the Great Plains or the Mid-Atlantic have no official boundaries at all, and people disagree about which states they include.