Tri-Cities is an appellation used to refer to several municipal areas in the United States, each of which consists mainly of three small cities of approximately the same size and regional importance.

The Tri-Cities of Michigan consist of Bay City, Saginaw, and Midland, located in the Saginaw Valley.

The Tri-Cities of Tennessee consist of Bristol, Kingsport, and Johnson City. Bristol, Virginia, a small town across the state line from Bristol, Tennessee, is often included.

The Tri-Cities of Washington consist of Richland, Pasco, and Kennewick, along the banks of the Columbia River.

North Carolina has two well-known "tri-cities" areas, the Triangle area (more formally, the Research Triangle of Raleigh, Durham, and Chapel Hill); and the Piedmont Triad of Greensboro, Winston-Salem, and High Point.

The cities of Moline and Rock Island in Illinois and Davenport in Iowa were formerly known as the Tri-Cities; with Bettendorf, Iowa, they are now commonly referred to as the Quad Cities. In suburban Chicago, the three far-western suburbs of St. Charles, Geneva and Batavia are known as the Tri-Cities of Illinois.

The three chief cities of New York's Capital District – Albany, Schenectady, and Troy – were once known as the "Tri-Cities."

The Colorado towns of Firestone, Frederick and Dacono are known to locals as the "tri-towns" or "tri-town area."

Wuhan is a collection of the towns of Wuchang, Hankou and Hanyang in the Hubei Province of China.