The 'AA' rating on Maricopa County Community College District (MCCCD), Ariz.'s GO bonds is based on the district's unlimited GO pledge and reflects: A broad and expanding economic base encompassing the diverse Phoenix metropolitan area; A very strong position of total unrestricted net assets, a diverse revenue base, and generally strong financial management; and Moderate but affordable direct and overlapping debt levels. These factors are somewhat limited by the district's dependence on state sources of revenue for a significant portion of its operating budget. The bonds are general secured by the district's ability to levy unlimited ad valorem taxes to pay bonds. Coterminous with Maricopa County in central Arizona, the district is the largest community college system in the nation,