The United States is gearing up for Cinco de Mayo. Music, all-day happy hours and deals on tacos are planned at venues across the country on Sunday — May 5 — in a celebration with widely misunderstood origins that is barely recognized south of the border.

In the U.S., the date is largely seen as a celebration of Mexican American culture stretching back to the 1800s in California. Typical festivities include parades, street food, block parties, mariachi competitions and baile folklórico, or folkloric dance, with whirling dancers wearing shiny ribbons with braids and bright, ruffled dresses.

For Americans with or without Mexican ancestry, the day has become an excuse to toss back tequila shots with salt and lime, and gorge on tortilla…