Border States
The 5 border states were Delaware, Kentucky, Maryland, Missouri, and West Virginia. These were the slave states that did not secede from the Union. In these states people were split between supporting the Union and the Confederacy. Each side took measures to persuade or even conquer areas to gain a border state's loyalty. Every state gave troops to both sides, and had both pro-Confederate and pro-Union governments. West Virginia was formed in 1863 when the northwestern part of Virginia (who remained loyal to the Union) seceded from the rest of the state. The split between the two sides was the most severe in the border states, and sometimes men from the same family fought on opposite sides. 170,000 soldiers fought for the Union while 86,000 fought for the Confederacy.
Map of the us during the civil war
Dark Blue= Union States Red= Confederate States Light Blue= Border States