In 1956 Sister Cities International began as an initiative by Dwight D. Eisenhower. He believed partnering cities around the world and connecting people at the community level would forge strong international relations and build trust, which would result in a more peaceful world. There are over 2,100 U.S. cities participating in the Sister Cities network. San Diego signed its first Sister City Agreement in 1957 with Yokohama, Japan and now has 16 sister cities.