The role of women in history was first commemorated in March 1978 as Women’s History Week in Sonoma County, California. Congress issued a joint resolution proclaiming a national Women’s History Week in 1981, and expanded the celebration to an entire month in 1987. Since then, Congress has designated every March as Women’s History Month.

The statistics collected by the U.S. Census Bureau reveal many facts about the changing female population of the United States over time. For example:

• The 1790 Census counted 1.5 million women (and almost 1.6 million men) living in the United States. On October 1 2010, there were 157 million women and 153 million men in the United States (Source: Population estimates).
• The median income of women who worked full time was $37,000 in 2009, compared to $19,000 (adjusting for inflation) in 1955. In comparison, men’s median income was $49,000 in 2009 and almost $30,000 in 1955.
• In 1960, women accounted for 4 percent of the employees in the protective services (such as firefighters and police officers) and 63 percent of education professionals. Today, women account for 22 percent of protective service employees and 69 percent of the education workforce (Source: 2005-2009 American Community Survey 5-Year Estimates).
• Prior to the passage of Title IX of the Education Amendments of 1972, 7 percent of all high school athletes [PDF 209.5 KB] were girls. In 2000, girls accounted for 42 percent of high school athletes (Source: Statistical Abstract of the United States).
• Between 1997 and 2007, the number of women-owned businesses increased from 5.4 million to 7.8 million. Today women own almost 29 percent of all businesses in the United States.

This Month in Census History: On March 31, 1951, the U.S. Census Bureau installed the UNIVAC I. The UNIVAC I was the first commercial, general-purpose data processing computer. It was used to tabulate part of the 1950 census of population and the 1954 economic census.