Sister Cities International | 5,507 followers on LinkedIn. To promote peace through mutual respect, understanding, and cooperation—one individual, one community at a time. | Our 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.