The outbreak of the American Civil War in 1861 led to the expansion of the federal government and notable growth in the city's population, including a large influx of freed slaves. President Abraham Lincoln signed the Compensated Emancipation Act in 1862, which ended slavery in the district, freeing about 3,100 slaves in the district nine months before the Emancipation Proclamation. In 1868, Congress granted the district's African American male residents the right to vote in municipal elections.