Arizona is a signatory to a boundary agreement with California (1963) and Nevada; and to such interstate accords as the Colorado River Compact, Desert Pacific Economic Region Compact, Interstate Compact for Juveniles, Interstate Oil and Gas Compact, Upper Colorado River Basin Compact, Western Interstate Commission for Higher Education, Wildlife Violator Compact, and Western Interstate corrections, nuclear, and education compacts.
The most important federal project in the state has been the Central Arizona Project, approved by Congress in 1968 and designed to divert water from the Colorado River to the Phoenix and Tucson areas for agriculture, energy, and other purposes. Federal grants totaled $5.2 billion in fiscal year 2001.