Direct dialing wasn't offered until the early 50s, but even the first proposal of area codes for MN in 1947 split it into two sections, 612 for Minneapolis and St. Paul and points southeast and the rest of MN for 218.

607 was introduced in 1954 for the southern fifth of the state (and exists unchanged now).

320 split 612 in 1996.

651 split St. Paul from 612 in late 1998 through early 1999. This was also part of a larger project that created 763 and 952 which broke off from 612 into the northern and southern part of the eastern Minneapolis suburbs so that 612 was left for downtown in 2000.

Correction, 607 is almost unchanged, as is 218.