To get to Tijuana from downtown San Diego by public transport, you can take the blue Trolley line in the direction of San Ysidro. This is probaly the most convinient way to get to Tijuana.
The ride with the trolley will take around 40 minutes. Once in San Ysidro, you get off, and right in front of you, you will see the Mexican border. In this area you will find some fast food restaurants and shops. To cross the border, follow the crowds (most of them Mexican workers). Walk up the stairs and walk along a bridge. After walking through two metal turnstiles, you will be in Mexico. Most of the times, nobody will control your papers when you travel to Mexico, but make sure you have your legal documents to go back to the US before crossing the turnstiles.
♥ Visit Tagulandang Island ♥