OK. First, let's clear things up: Cinco de Mayo is not the celebration of Mexican Independence Day. In fact, it is in celebration of the relatively minor Battle of Puebla, when in 1862, Mexican forces defeated the French Army - like that's any big accomplishment. Anyway, somehow, the day turned into an American celebration, and in turn, co-opted by the alcohol companies into a drinking holiday like St. Patrick's Day and Halloween.
Cynicism aside, San Diego does have Mexican roots (unlike, say, Iowa), and we are the birthplace of California. So, we can justify any sort of Cinco de Mayo festivities, OK?

Getty ImagesWith our Mexican heritage, what better place to celebrate Cinco de Mayo than at Old Town State Historic Park. The Old Town San Diego Fiesta Cinco de Mayo in historic Old Town San Diego along San Diego Avenue will be held May 3 and 4, 2008. This family friendly, free event is the west coast’s premiere celebration of arts and culture and the signature event of Old Town. The event features music, food, handcrafts and Southern California’s only reenactment of the 1862 Battle of Puebla. Event Dates: Saturday, May 2nd and Sunday, May 3rd, 2009. Event Times: Saturday, 12:00p.m. - 10:00p.m.; Sunday, 10:00a.m. - 5:00p.m. Information for Fiesta Cinco de Mayo: 619.296.3236
The 12th Annual Cinco de Mayo to be held Sunday, between E and G Streets will feature live entertainment by the Southwestern College School of Arts and Communication; authentic Mexican food and beverages from different Third Avenue Village restaurants and other food vendors; arts and crafts; a kids’ fun zone with mechanical rides; singing, dancing, and salsa contests at our main F Street stage; a Beer Garden at Maria Cadenlaria Mexican Restaurant from 11am to 7pm with beer and appetizer specials, located at 323 Third Avenue; a Quinceaňera event and fashion show at Memorial Park Bowl; and best of all, admission is free.
3. Oceanside Cinco de Mayo Fiesta En La Playa
Oceanside will celebrate Cinco de Mayo Fiesta, Univision’s annual Latino Fiesta, with live entertainment, sponsors, and food booths, at the Oceanside Pier Amphitheatre on May 3, 2009. Located near Oceanside Pier, Oceanside's Cinco D Mayo is sponsored by Univision’s annual Latino Fiesta. May 3, 2009, 11:30am - 5pm, Pier Plaza Amphitheatre, 200 N the Strand, Oceanside, CA
(858) 576-1919.Another not-quite Cinco de Mayo festival, but the Carlsbad Village Street Fair takes place on May 3, 2009, so that's good enough reason to take in this huge annual street festival, which undoubtedly will feature Cinco-related festivities. The Village Faire features over 850 unique vendors with a little of everything: arts & crafts, antiques, unique clothing, items from around the world, and more. Children's rides, an international food center, and an old-fashioned pancake breakfast guarantee that you'll find fun for the whole family. Sunday, May 3, 2009. 8:00am to 5:00pm