United States map of 1861, showing affiliation of states and territories regarding secession from the Union at the start of the American Civil War.
Legend:

  States that seceded before April 15, 1861
  States that seceded after April 15, 1861
  States that permitted slavery, but did not secede
  States of the Union where slavery was banned
  U.S. territories, under Union Army control
This vector image was created with Inkscape, and then manually edited
Júlio Reis