sentences:  As of 1776, slavery was legal in all 13 colonies, but by Washington's death in December 1799 there were eight free states and nine slave states, and that split was considered entirely constitutional.The support of the southern states for the new constitution was secured by granting them concessions that protected slavery, including the Fugitive Slave Clause, plus clauses that promised Congress would not prohibit the transatlantic slave trade for twenty years, and that empowered (but did not require) Congress to authorize suppression of insurrections such as slave rebellions.The Constitution also included the Three-Fifths Compromise which cut both ways