Columbia subject headings:
Poor--Political activity--United States.
Poor--United States--Political activity.
Voter registration--United States.
Voting--United States--Abstention.
Harvard subject headings:
Poor--Political activity--United States.
Poor--United States--Political activity.
Voter registration--United States.
Voting--United States--Abstention.
Princeton subject headings:
Poor--United States--Political activity.
Voter registration--United States.
Voting--United States--Abstention.