American taxpayers get an extra three days to file their federal tax returns this year.

The filing deadline is delayed until midnight Monday, April 18 because the District of Columbia will observe Emancipation Day on Friday, April 15, the traditional tax filing deadline.

By law, local holidays in the nation's capital affect tax deadlines the same way federal holidays would. States generally follow the federal deadline.

Emancipation Day marks the occasion when President Abraham Lincoln signed a law ending slavery in the District of Columbia. Lincoln signed it April 16, 1862, more than eight months before he signed the Emancipation Proclamation, which ultimately freed all of the slaves when the Civil War came to an end.