Home > Mean center of U.S. population

the point at which an imaginary, flat, weightless, and rigid map of the United States would balance perfectly if weights of identical value were placed on it so that each weight represented the location of one person on the date of the census.

During the 20th century, the mean center of population has shifted 324 miles west and 101 miles south. The southerly movement was much stronger during the second half of the century; 79 of the 101 miles happened between 1950 and 2000. It may not be a coincidence that it was after World War II that room air conditioning unit sales increased dramatically. According to the Air Conditioning and Refrigeration Institute [1], 30,000 room air conditioners were sold in 1946, a number that increased to over 1,000,000 by 1953.

The following counties included the mean center of U.S. population during the 20th century:

• 1900 Bartholomew County, Indiana
• 1910 Monroe County, Indiana
• 1920 Owen County, Indiana
• 19301930 is the common year starting on Wednesday. see link for calendar) Events January-February January 6 The first diesel-engine automobile trip is completed ( Indianapolis, Indiana, to New York City). January 27 Miguel Primo de Rivera resigns January 30 G Greene County, IndianaGreene County is a county located in the U. State of Indiana, and determined by the U. Census Bureau to include the mean center of U. population in 1930. As of 2000, the population is 33,157. The county's county seat is Bloomfield, Indiana. Geography Acco
• 1940Events January-February January 5 FM radio is demonstrated to the FCC for the first time. January 6 World War II: Mass execution of Poles, committed by Germans in the Poznan, Warthegau. January 12 World War II: Russia bombs cities in Finland. February 2 F Sullivan County, IndianaSullivan County is a county located in the U. State of Indiana, and determined by the U. Census Bureau to include the mean center of U. population in 1940. As of 2000, the population is 21,751. The county's county seat is Sullivan, Indiana. Geography Acco
• 1950 Clay County, IllinoisClay County is a county located in the U. State of Illinois, and determined by the U. Census Bureau to include the mean center of U. population in 1950. As of 2000, the population is 14,560. Its name is in honor of Henry Clay, famous American statesman, m
• 1960Events January-February January 1 Independence of Cameroon January 9 Aswan High Dam construction begins in Egypt January 11 Chad declares its independence. January 14 Ralph Chubb, the gay poet and printer, dies at Fair Oak Cottage in Hampshire. January 23 Clinton County, IllinoisClinton County is a county located in the U. State of Illinois, and determined by the U. Census Bureau to include the mean center of U. population in 1960. As of 2000, the population is 35,535. Its name is in honor of the seventh Governor of New York Stat
• 1970Events January events January 1 Construction begins on Arcosanti, by Paolo Soleri, in Mayer, Arizona, located 65, miles north of Phoenix, Arizona. January 1 Unix epoch at 00:00:00 UTC. January 12 Biafra capitulates, ending the Nigerian civil war. January St. Clair County, Illinois
• 1980 Jefferson County, Missouri
• 1990 Crawford County, Missouri
• 2000 Phelps County, Missouri

The addition of Alaska and Hawaii to the union had the effect of moving the center about two miles farther south and about ten miles farther west for 1960.