Frontier Strip

The Frontier Strip are the six states in the United States forming a north-south line from North Dakota to Texas. In the American Old West, westward from this strip was the frontier of the United States toward the latter part of the 19th century. The Frontier Strip states, or the Last American Frontier, form a nearly straight line from north to south and roughly correspond to the Great Plains region of the United States.

The term Frontier Strip is correlated to the 1880 census, where these six states, some of which were territories at the time, were part of the "Frontier Line," sometimes taken to be the 100th meridian west, the geographic designation by the U.S. Census Bureau that proclaimed where the civilization of the Eastern United States ended and the historic American Wild West began. In the 1890 census, it stated, "Up to and including 1880 the country had a frontier of settlement, but at present the unsettled area has been so broken into by isolated bodies of settlement that there can hardly be said to be a frontier line. In the discussion of its extent, its westward movement, etc., it can not, therefore, any longer have a place in the census reports."

The Frontier Strip's land area is 1,642,083.585 km² (634,012.017 sq mi), or 17.92% of U.S. land area. Its population as of the 2000 census was 30,099,199 or 10.695% of U.S. population. Its average population density was 18.33/km² (47.47/sq mi), compared to the U.S. average of 30.72/km² (79.56/sq mi). Its population is heavily tilted towards the south, with both population and population density increasing as one goes state by state from North Dakota in the north towards Texas in the south. Texas by itself has 69.28% of the region's population, living on 41.29% of its land area.

...
Wikipedia