From the US Census Bureau:

National Women’s History Month’s roots go 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.

161 million
The number of females in the U.S. as of December 2013. The number of males was 156.1 million. Source: U.S. Census Bureau, Monthly Postcensal Resident Population: 7/1/2013 – 12/1/2013 http://www.census.gov/popest/data/national/asrh/2012/2012-nat-res.html

2 to 1
At 85 and older, the approximate ratio by which women outnumbered men in 2012 (3.9 million to 2.0 million). Source: U.S. Census Bureau, Population Estimates http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=PEP_2012_PEPAGESEX&prodType=table

Jobs

75 million
The number of females 16 and older who participated in the labor force in 2012. Women comprised 47.2 percent of the labor force in 2012. Source: U.S. Census Bureau, 2012 American Community Survey, DP03 http://factfinder2.census.gov/bkmk/table/1.0/en/ACS/12_1YR/DP03

41.6%
Percent of employed females 16 and over in 2012 (annual average) who worked in management, professional and related occupations, compared with 34.7 percent of employed males in the same year (annual average). Source: U.S. Bureau of Labor Statistics, Current Population Survey http://www.bls.gov/cps/cpsaat09.htm

Military

1.6 million
Number of female veterans in the United States in 2012. Source: 2012 American Community Survey http://factfinder2.census.gov/bkmk/table/1.0/en/ACS/12_1YR/B21001/0100000US

Earnings

$37,791
The median annual earnings of women 15 or older who worked year-round, full time in 2012. In comparison, the median annual earnings of men were $49,398. Source: Income, Poverty, and Health Insurance Coverage in the United States: 2012, Page 7. http://www.census.gov/prod/2013pubs/p60-245.pdf

77¢
The amount that female year-round, full time workers earned in 2012 for every dollar their male counterparts earned. This ratio was statistically unchanged from 2011. Source: Income, Poverty, and Health Insurance Coverage in the United States: 2012, Page 11. http://www.census.gov/prod/2013pubs/p60-245.pdf

Education

11.3 million
Number of women college students in fall 2012. Women comprised 56.8 percent of all college students. Source: School Enrollment in the United States: 2012, Table 5 http://www.census.gov/hhes/school/data/cps/2012/tables.html

31.4
Percent of women 25 and older who had obtained a bachelor’s degree or more as of 2013. Source: Educational Attainment in the United States: 2012, Table 3 http://www.census.gov/hhes/socdemo/education/data/cps/2013/tables.html

25%
Percentage of women 18 and older with an alternative educational credential — such as professional certifications, licenses and educational — not statistically different from men. However, women had higher rates of alternative credentials than men at the bachelor’s degree and advanced degree levels. Source: Measuring Alternative Educational Credentials: 2012 http://www.census.gov/prod/2014pubs/p70-138.pdf

15%
Among people with advanced degrees, the percentage of women who held educational certificates compared with 12 percent of men; 51 percent of women held professional certifications or licenses compared with 43 percent of men. Source: Measuring Alternative Educational Credentials: 2012 http://www.census.gov/prod/2014pubs/p70-138.pdf

Voting

63.7%
Percentage of female citizens 18 and older who reported voting in the 2012 presidential election, in comparison to 59.7 percent of their male counterparts. Source: Voting and Registration in the Election of November 2012, Table 2 http://www.census.gov/hhes/www/socdemo/voting/publications/p20/2012/tables.html

Motherhood

85.4 million
Estimated number of mothers in the U.S. in 2009. Source: Unpublished data from the Survey of Income and Program Participation

1.9
Average number of children that women 40 to 44 had given birth to as of 2010, down from 3.1 children in 1976, the year the Census Bureau began collecting such data. Source: Fertility of American Women: 2010 table 2 and Historical table 2 http://www.census.gov/hhes/fertility/data/cps/
The percentage of women in this age group who had given birth was 81 percent in 2010, down from 90 percent in 1976. Source: Fertility of American Women: 2010 table 1 and Historical table 2 http://www.census.gov/hhes/fertility/data/cps/

Marriage

66 million
Number of married women 18 and older (including those who were separated or had an absent spouse) in 2013. Source: Families and Living Arrangements: 2013, Table A1 http://www.census.gov/hhes/families/files/cps2013/tabA1-all.xls

5.2 million
Number of stay-at-home mothers nationwide in 2013; compared with 214,000 stay-at-home fathers. Source: Families and Living Arrangements: 2013, Table FG8 http://www.census.gov/hhes/families/files/cps2013/tabFG8-all.xls