Area code 612

Area code 612 is part of the North American Numbering Plan of the public switched telephone network for the city of Minneapolis, Minnesota and a few surrounding areas such as Fort Snelling, St. Anthony and Richfield. By geographical area, it is the smallest area code in the state of Minnesota. However, like many other metropolitan area codes in the United States, the region used to be much larger, accounting for the entire Twin Cities region and a wide area surrounding it.

At the outset, Minnesota received two area codes, 612 and 218. A 1947 map of the NANP showed the region defined as roughly the southeastern third of Minnesota. The rest of the state was 218, which formed an r-shaped region around the 612 area code. The separating line extended westward from Duluth to the center of the state, then down through the center.

Wikipedia