SISTER CITIES INTERNATIONAL SISTER CITIES INTERNATIONAL Mission: To promote peace through mutual respect, understanding, and cooperation — one individual, one community at a time. Founded by President Dwight D. Eisenhower in 1956, Sister Cities International is a nonpartisan 501(c)(3) nonprofit which serves as the national membership organization for individual sister cities, counties, and states across the U.S. This network unites tens of thousands of citizen diplomats and volunteers in 545 communities with over 2,100 partnerships in 145 countries on six continents.