The House of Representatives passed the Tallmadge Amendment in 1819 because the amendment had already passed in the Senate.
The Tallmadge Amendment was a bill proposed on 13 February 1819 by Rep. James Tallmadge of New York in order to amend Missouri improving legislation by forbidding the introduction of slavery into Missouri and declaring that all children born of slave parents after the admission of the state should be free upon reaching the age of twenty-five.