San Ysidro is well recognized as the home to the world's most bustling land border in the United states. This is where adventurous folks go to travel between the city of San Diego to Tijuana, Mexico. San Ysidro is a densely populated urban city located just North of the United States Mexican border. This humble neighborhood is a district in the Southern region of San Diego close to where the US Interstate 5 crosses into Mexico. This modest community consists of small homes and studio apartments..San Ysidro has a large group of residents rich in Mexican ancestry.