Mexican Americans in Los Angeles - Hardcoverby Alex Moreno Areyan (Author) Mexican Americans established and nurtured the foundation, fiber, and fabric of Los Angeles since the first pobladores arrived in 1781. Pride in family, work, community, and religion coalesces into their legacy from East Los Angeles to the San Fernando Valley to the port areas of Wilmington and San Pedro. Men and women of Mexican heritage comprised 47 percent of Los Angeles County's Latino population in the 21st century.