SAN DIEGO — Mayors from Mexico and San Diego came together for a special celebration of cross-border culture and collaboration.

They met at the third U.S.-Mexico Mayors’ Community Summit put on by Sister Cities International to promote citizen diplomacy.

Over the next three days, mayors from across the U.S. and Mexico will be exchanging ideas on how to tackle some of the most pressing issues facing border region.

“In San Diego, we have 21 sister cities in 20 different countries and two of those are with Mexico,” said Dr. Michael McQuary of Sister Cities International.

Mayors and business and community leaders from both the U.S. and Mexico came together to address issues like unauthorized border crossings and sewages spills from Mexico.

“Much of the solutions to that are at the federal level,” San Diego Mayor Todd Gloria said. “What mayors can do is work on a local level and often what we can find is progress that you can not find at a national level of politics.”

Gloria says nearly half-a-billion dollars have been assembled to clean the Tijuana River Valley. He also toured the creation of a new port of entry east of Otay Mesa.

“This will dramatically reduce wait times and therefore improve quality of life, increase our economic opportunities on both sides of the border. It’s one of the things we want to illustrate today,” Gloria said.

Leaders say cross-border collaborations is needed because what happened on one side of the border affects the other side.

“It’s very important because we are like Washington which is far from San Diego. We are far from Mexico City, which is the federation. We protect each other. Between both nations, we protect each other,” Tijuana Mayor Monserrat Caballero said.

This is the first night of the three day summit. On Wednesday, the Mayors are expected to meet in Tijuana.