The presidency of Thomas Jefferson began on March 4, 1801, when he was inaugurated as the third President of the United States, and ended on March 4, 1809. The presidency of Thomas Jefferson began on March 4, 1801, when he was inaugurated as the third President of the United States, and ended on March 4, 1809. Jefferson assumed the office after defeating incumbent President John Adams in the 1800 presidential election. The Constitution had included a provision preventing Congress from enacting a law banning the importation of slaves until 1808. In the years before Jefferson took office, the growing fear of slave rebellions led to diminished enthusiasm in the South for the abolition of slavery, and many states began to enact Black Codes designed to restrict the behavior of free blacks. During his presidential term, Jefferson was disappointed that the younger generation was making no move to abolish slavery; he largely avoided the issue until 1806. He did succeed in convincing Congress to block the foreign importation of slaves into the newly purchased Louisiana Territory.