In 1998, the Transportation Equity Act for the 21st Century (TEA-21), authorized the states to retain the federal share of proceeds from the sale or lease of real property that had been purchased with federal-aid funds. It also required the states to use the federal share on other highway projects eligible for funding under the federal-aid highway program. GAO determined (1) the extent to which states are selling, leasing, or disposing of real property purchased with federal-aid funds and (2) how the proceeds generated from the sale or lease of real property are being used, including whether they are being used in accordance with TEA-21. GAO issued a related legal opinion in September 2002.