The Willey Amendment resolved the issue of slavery in West Virginia, clearing the way to admit the new state into the Union. In 1861, voters west of the Allegheny Mountains rejected Virginia's secession from the United States and instead opted to create a loyal Reorganized Government of Virginia. It was only a matter of time until West Virginia was created. Among the constitutional issues to be addressed was the question of slavery, which existed in parts of the proposed new state. Sentiment in the western counties was sharply divided. Some preferred to retain slavery, some favored total abolition, and some favored gradual emancipation. Still others sought to exclude Blacks from the new state entirely.

The matter went before the U.S. Senate. Radical Republican Charles Sumner of Massachusetts proposed to free all enslaved people in West Virginia as of July 4, 1863. His proposal was defeated, and Reorganized Government of Virginia Sen. Waitman Willey suggested that children born to enslaved mothers after July 4, 1873, should be freed. This proposal in turn was not acceptable to senators wishing to eliminate slavery, a concept for which they felt the North was fighting the Civil War. Willey then managed to strike a compromise that was acceptable to a majority. The Willey Amendment to the West Virginia Statehood Bill provided that all enslaved people under 21 years of age on July 4, 1863, would be free on reaching that age. The compromise, adopted by the convention on February 17 and later superseded by the 13th Amendment to the U.S. Constitution, led to the passage of the statehood bill and resulted in the creation of West Virginia on June 20, 1863.

The following is the text of the Willey Amendment:

The children of slaves born within the limits of this State after the fourth day of July, eighteen hundred and sixty-three, shall be free; and all slaves within the said State who shall, at the time aforesaid, be under the age of ten years, shall be free when they arrive at the age of twenty-one years; and all slaves over ten and under twenty-one years, shall be free when they arrive at the age of twenty-five years; and no slave shall be permitted to come into the State for permanent residence therein.