The war brought tremendous change to California society. In the five years after 1940, California's population grew by 2.5 million or 30%. Accompanying this growth, pressure would be placed on the state's infrastructure and government, forcing them to expand as well. The rush to expand production and replace the men who went into the military opened up opportunities for women and minorities. Of the six million women who entered the national workforce, 40% found employment in California defense industries. Black Americans also benefited from the demand for laborers. California saw a threefold increase in the black population. Also, tens of thousands of “Dust Bowl” farm laborers escaped California's fields to find higher wages in defense plants. Because of the relocation of Japanese farmers and the flight of Dust Bowl migrants, farms faced labor shortages. In 1942, negotiations with Mexico would fill this labor force gap. Over 309,000 laborers were imported to work on US farms; 219,000 came from Mexico. Instant cities grew up around Bay Area and Los Angeles shipyards which employed over 300,000 workers. This rapid growth put tremendous strain on many communities – e.g., housing shortages, and scarce emergency, health, and social services.