Although the “importation” of slaves into the United States was outlawed by federal law from 1808, the domestic trade in slaves continued to be a major economic activity. Maryland and Virginia, for example, would "export" its surplus slaves to the south. (See Franklin and Armfield Office.) Enslaved family members could be split up (ie., sold off) never to see or hear of each other again. Between 1830 and 1840, nearly 250,000 slaves were taken across state lines. In the 1850s, more than 193,000 were transported, and historians estimate nearly one million in total were traded. Slavery itself was abolished in the 1860s.