List of U.S. National Historic Landmarks by state

The United States National Historic Landmark Program is designed to recognize and honor the nation's cultural and historical heritage. The program was formally inaugurated with a series of listings on October 9, 1960; as of August 21, 2020, there are 2,597 designated landmarks.

Source: Wikipedia — List of U.S. National Historic Landmarks by state (CC BY-SA 4.0)