After historically describing the formation process of the 200-foot square block in Portland, Oregon, which is said to be the smallest in the U.S.A., the following findings were made based primarily on Sanborn maps: 1. There are several other cities with blocks of almost the same small size. 2. To capitalize on the economic advantages of corner lots, the block was initially divided into eight sections. However, the most sections were integrated and subdivided while maintaining their form. 3. There are no backstreets in the city, so all activities take place on the main streets.