Immigrant farm workers during the Dirty Thirties used a route that connected what states?
U.S. Route 99: U.S. Route 99 (US 99) was a main north–south United States Numbered Highway on the West Coast of the United States until 1964, running from Calexico, California, on the US–Mexico border to Blaine, Washington, on the U.S.-Canada border. Dust Bowl: The Dust Bowl, also known as the Dirty Thirties, was a period of severe dust storms that greatly damaged the ecology and agriculture of the American and Canadian prairies during the 1930s; severe drought and a failure to apply dryland farming methods to prevent wind erosion (the Aeolian processes) caused the phenomenon.
Calexico, California, on the US–Mexico border to Blaine, Washington, on the U.S.-Canada border