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 slaves 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 slave 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 which was acceptable to a majority. The Willey Amendment to the West Virginia Statehood Bill provided that all slaves 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 The compromise, adopted by the convention on February 17 and later superseded by the 13th Amendment to the U.S. Constitution, led to the passage of the statehood bill and resulted in the creation of West Virginia on June 20, 1863.