Census History: Civil War Sesquicentennial
"This month begins the sesquicentennial – the 150th anniversary – of the Civil War. The war began on April 12, 1861, when Confederate troops opened fire on Fort Sumter, near Charleston, SC.

Data collected by the US Census Bureau help paint a portrait of our nation during 1861. For example:

• The censuses of 1850 and 1860 asked questions about freed and escaped slaves, and revealed that more slaves were freed in 1860 than in 1850. In addition, the number of slaves who escaped from Mississippi, Missouri, and Virginia increased in 1860, compared to 1850.

• The 1860 Census, taken before the start of the Civil War, recorded nearly 4 million slaves in the nation..."