Which state separated from Virginia due to its anti-slavery sentiments and remained loyal to the Union?

West Virginia is the correct answer because it was formed during the Civil War by a group of residents in the northwestern region of Virginia who opposed secession from the Union. The western counties, which were more agrarian and less dependent on slave labor than the rest of Virginia, were concerned that their interests were not being represented in the state legislature, especially as the majority of Virginia aligned with the Confederacy. In 1863, following a series of conventions and legislative actions, West Virginia was admitted to the Union as a separate state.

This historical context underscores West Virginia's unique position as a state that separated from Virginia due to differing economic and social views regarding slavery and allegiance during the Civil War. It was the only state created from another state during the war and became a significant symbol of loyalty to the Union amidst a backdrop of conflict and division.