How Argentine ants conquered the world
Argentine ants reached California and the rest of the world by traveling on cargo ships, trains, and later trucks. They first came to the U.S. by ship from Puerto Rosario in Argentina, and landed in the Port of New Orleans. There, they hopped on the Sunset Limited train to Los Angeles. In red, you can see the 19th and 20th century shipping routes that the ants took between Puerto Rosario and the United States. The blue line is the Sunset Limited, which ran between New Orleans and Los Angeles in the early 20th century.
This map was created with Mapzen's Tangram, thanks to a great deal of help from @burritojustice.