who abolished slavery when he issued the emancipation proclamation in 1863, this meant that slavery could continue in the United States

Lincoln

Explanation:

Three days later, Lincoln went public with the preliminary Emancipation Proclamation, which called on all Confederate states to rejoin the Union within 100 days-by January 1, 1863-or their slaves would be declared "thenceforward, and forever free."

Abraham Lincoln signed the emancipation procli