The 1870 census commenced on June 1, 1870, and was taken under the provisions of the Census Act of May 23, 1850. The Secretary of Interior appointed General Francis A. Walker Superintendent of the Ninth Census on February 7, 1870.
The 1870 census marked the first enumeration following the end of slavery and, therefore, counted all inhabitants of the United States on a single population schedule. The 1870 enumeration was completed on August 23, 1871, and a portion of the data was processed using a machine invented by Charles W. Seaton.
At its conclusion, the 1870 census reported the U.S. resident population as 38,558,371, a 26.6 percent increase from 1860.