While significant numbers live in Mexico year round, it is probable that a majority of these residents do not stay the whole year. Retirees may live half a year in the U.S. to keep retiree benefits. Those called "snowbirds" come in autumn and leave in spring. The American community in Mexico is found throughout the country, but there are significant concentrations of U.S. citizens in all the north of Mexico, especially in Tijuana, Mexicali, Los Cabos, San Carlos, Mazatlán, Saltillo, Monterrey and Nuevo Laredo, and also in the central parts of the country such as San Miguel de Allende, Ajijic, Chapala, Mexico City and Cuernavaca, and along the Pacific coast, most especially in the greater Puerto Vallarta area. In the past few years, a growing American community has developed in Mérida, Yucatán.