Emancipation Day in DC
Tax Day is traditionally April 15. So, why is it April 18 this year? You can thank Emancipation Day for your three-day reprieve. Here's why:
The standard: If April 15 falls on the weekend, the tax deadline is moved to Monday.
This year: Emancipation Day, April 16, is a legal holiday only in Washington, D.C.  Since it falls on a Saturday this year, it will be observed April 15. A federal statute says tax filings are impacted nationwide, so this year's tax deadline is Monday. (And you thought nothing good ever came out of D.C.)
Next, let's get some background on Emancipation Day and how slavery ended in the U.S.

The Compensated Emancipation Act
On April 16, 1862, President Abraham Lincoln signed the Compensated Emancipation Act , which freed all slaves within the District of Columbia, the first in the nation to be freed by the federal government. The more famous Emancipation Proclamation took effect 36 weeks later, but the District of Columbia continues to celebrate Emancipation Day on the anniversary of the first act.
Proclamations notwithstanding, America's slaves weren't all freed at the same time. (In Texas, for example, emancipation took effect as late as Juneteenth in 1865.)
Let's look at how slavery ended state by state.
Gradual emancipation
The following states passed their own gradual emancipation laws, designed to phase out the institution of slavery over a period of time.

Massachusetts
Year passed
Note: State constitution adopted with freedom clause, which courts interpreted as prohibiting slavery

Pennsylvania

Rhode Island

 Connecticut

New York

New Jersey

 New Hampshire

Granted statehood as a 'free' state

While in many cases slavery had already been abolished when they were territories, the following states were admitted into the Union as "free" states:

Vermont

Ohio

Indiana

Illinois

Maine

Michigan

Iowa

Wisconsin

California

Minnesota

Oregon

Kansas

Freed by the Emancipation Proclamation

Lincoln's Emancipation Proclamation of 1863 ended slavery in the following states that had seceded, provided the Union won the war:

Alabama

Arkansas

Florida

Georgia

Louisiana

Mississippi

North Carolina

South Carolina

Tennessee

Texas

Virginia

Freed by the 13th Amendment

In 1865, the ratification of the 13th Amendment to the U.S. Constitution ended slavery in the following "slave slates" that had not seceded (and throughout the nation):

Delaware


Kentucky


Maryland

Missouri


West Virginia

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