What were the states that did not secede known as?

The states that did not secede from the Union during the American Civil War were known as the "Union states" or "loyal states." These included states like New York, Pennsylvania, and Illinois, among others. Some of them were slave states that remained loyal to the Union, often referred to as the "Border States," such as Kentucky and Missouri. The Union states played a crucial role in the war effort against the Confederacy.