Uruguay is distinguished by its high literacy rate, large urban middle class, and relatively even income distribution. The average Uruguayan standard of living compares favorably with that of most other Latin Americans. Metropolitan Montevideo, with about 1.4 million inhabitants, is the only large city. The rest of the urban population lives in about 20 towns. During the past two decades, an estimated 500,000 Uruguayans have emigrated, principally to Argentina and Spain. Emigration to the United States also rose significantly. As a result of the low birth rate, high life expectancy, and relatively high rate of emigration of younger people, Uruguay's population is quite mature.