Columbia subject headings:
Harvard subject headings:
United States--Civilization--21st century.
United States--Economic conditions--21st century.
United States--Politics and government--2009-2017.
United States--Race relations--History--21st century.
United States--Social conditions--21st century.
Princeton subject headings:
United States--Civilization--21st century.
United States--Economic conditions--21st century.
United States--Social conditions--21st century.