Columbia subject headings:
Secession.
United States--Politics and government--1861-1865.
Harvard subject headings:
Secession--Southern States.
Secession.
Unionists (United States Civil War)
United States--History--Civil War, 1861-1865
United States--Politics and government--1861-1865.
Princeton subject headings:
Secession.
United States--Politics and government--1861-1865.