US Senate
Trends in Congressional Appropriations [Pdf]
Provides numerous graphs accompanied by explanations of the government spending since the 1960s. Focuses on the restraint of the 1990s but shows the steady growth in the last forty years. Link to .pdf file. Requires Adobe Reader.
iCivics
I Civics: Government Spending
This lesson focuses on a variety of topics related to government spending, including the federal budget, mandatory versus discretionary spending, and government debt.