The holiday honors a 19th-century battle between the French and the Mexican armies that, strangely enough, may have influenced the outcome of the US Civil War.

Guacamole has been spared from tariffs for now. But salsa may not be so lucky. While threatened tariffs on Mexican avocados have been put on pause, the U.S. government plans to put a nearly 21% duty on fresh Mexican tomatoes starting July 14.

It's actually more popular in the United States than in Mexico. And it may have helped tip the American Civil War in favor of the Union.