March is National Women’s History Month, which dates back to March 8, 1857, when women from New York City factories staged a protest over working conditions. International Women’s Day was first observed in 1909, but it wasn’t until 1981 that Congress established National Women’s History Week to be commemorated the second week of March. In 1987, Congress expanded the week to a month. Every year since, Congress has passed a resolution for Women’s History Month, and the President has issued a proclamation. Here are some facts about women from the U.S. Census Bureau:

157.2 million: The number of females in the United States as of October 1, 2010. The number of males was 153.2 million.

82.8 million: Estimated number of mothers in the United States.

77 cents: Women earn 77 cents for every $1 earned by men.

29.9 million: Number of women 25 and older with a bachelor’s degree or more in 2009, higher than the corresponding number for men (28.7 million). Women had a larger share of high school diplomas, as well as associate, bachelors and master’s degrees.

141,892: There were 141,892 women-owned businesses with receipts of $1 million or more in 2009.

7.8 million: The number of women-owned businesses in 2007.

13%: Percentage of women-owned businesses in California in 2007, which had the most women-owned businesses at 1 million. Texas was second with 610,162 or 8% of all women-owned businesses. New York was third with 594,421, accounting for 7.8%.

111,000: Number of female police officers across the country in 2009. In addition, there were about 9,700 women firefighters, 338,000 lawyers, 294,000 physicians and surgeons, and 38,000 pilots.

197,900: Total number of active duty women in the military, as of September 30, 2008.

20.7%: Percentage of married couples in which the wife earned at least $5,000 more than the husband in 2010.

[Via:  U.S. Census Bureau]