Government: Constitution of 1917 in force in 1997. Formally a federal republic, although federal government dominates governments of thirty-one states and Federal District. Central government power concentrated in president, who directs activities of numerous agencies and state-owned business enterprises. Bicameral legislature comparatively weak. Federal judiciary headed by Supreme Court of Justice. State governments headed by elected governors; all states have unicameral legislatures; state courts subordinate to federal courts. Federal District governed by mayor (regente) indirectly elected by legislative body of the Federal District beginning in 1996; more than 2,000 local governments headed by elected municipal presidents and municipal councils.

Foreign Relations: Major attention devoted to United States. Trade and immigration along shared border subjects of continuing negotiations. Foreign policy traditionally based on international law; nonintervention the major principle. Widely active in hemispheric affairs, including good relations with Cuba.