Spending was chosen because corrections is a narrow function consisting of a few specialized and interrelated activities; more than three-fourths of State corrections expenditures are directed at the primary task of caring for State prisoners through the construction, operation, and maintenance of prison facilities. The expenditure data covered both operating and capital costs. The costs were calculated in terms of both spending per State resident and spending per inmate. Results revealed declining differences in State expenditures, particularly during the last few decades and particularly when calculated per inmate. Possible competing explanations for the decline in State spending differences include increased judicial activism congressional policymaking at the national level. However, the patterns indicate other possible confounding factors, including specific patterns in certain subsets of States. Figure, footnotes, and 57 references (Author abstract modified)