Columbia subject headings:
Postal service--United States--Finance.
United States Postal Service--Appropriations and expenditures.
Harvard subject headings:
Postal service--United States--Finance.
United States Postal Service--Appropriations and expenditures.
Princeton subject headings:
Postal service--United States--Finance.
Subsidies--United States.
United States Postal Service--Appropriations and expenditures.
United States. Congressional Budget Office