Population per Square Mile
Continental United States.—The following summary shows, for continental United States, the total population, land area in square miles, and population per square mile of land area at each census from 1790 to 1910, inclusive:
| Census Year | Population | Land area (square miles) | Population |
|---|---|---|---|
| 1910 | 91,972,266 | 2,973,890 | 30.9 |
| 1900 | 75,994,575 | 2,974,159 | 25.6 |
| 1890 | 62,947,714 | 2,973,965 | 21.2 |
| 1880 | 50,155,783 | 2,973,965 | 16.9 |
| 1870 | 38,558,371 | 2,973,965 | 13.0 |
| 1860 | 31,443,321 | 2,973,965 | 10.6 |
| 1850 | 23,191,876 | 2,944,337 | 7.9 |
| 1840 | 17,069,453 | 1,753,588 | 9.7 |
| 1830 | 12,866,020 | 1,753,588 | 7.3 |
| 1820 | 9,638,453 | 1,753,588 | 5.5 |
| 1810 | 7,239,881 | 1,685,865 | 4.3 |
| 1800 | 5,308,483 | 867,980 | 6.1 |
| 1790 | 3,929,214 | 867,980 | 4.5 |
According to the census of 1910, there are in continental United States, on the average, 30.9 inhabitants to each square mile of land area, or nearly seven times the number per square mile shown for the much smaller area of 1790, and nearly three times the number shown for 1860. The decrease in the average number of inhabitants per square mile at the census of 1810 and 1850 was due in each case to large accessions of thinly populated territory during the decade preceding the census.
In the order of their density of population the nine geographic divisions of the country rank as follows: Middle Atlantic, 193.2 inhabitants per square mile; New England, 105.7; East North Central, 74.3; East South Central, 46.8; South Atlantic, 45.3; West North Central, 22.8; West South Central, 20.4; Pacific, 13.2; and Mountain, 3.1. The changes in density from census to census correspond precisely with the changes in area and the total number of inhabitants. It may be noted, however, that on account of the rapid increase in their population the Pacific states in 1910 for the first time are approaching, in density of population, conditions found in the states between the Mississippi River and the Rocky Mountains.
Porto Rico.—Porto Rico contains about 3,600 square miles, and has a population of considerable more than a million. The climate is tropical and the land is extremely fertile.
Postage Stamps.—They were invented in 1834, and were introduced into America in 1847.
Poultry and Egg Industry.—Nearly 500,000,000 of poultry, including chickens, turkeys, geese, and pigeons, are raised in the United States annually. The total value is about $203,000,000. Each year the production of eggs is about 1,600,000,000 dozen. The people of the United States eat about 5-1/2 fowls per year per capita, and a little over 17 dozen eggs.