1936
People's State Bank of Parshall, ND opens it doors.
1964
Darold Petersen joins Lakeside State Bank in New Town, ND as President. Over time the Petersen family purchases controlling interest and today remains Cornerstone Bank's largest shareholder.
1982
The Petersen family expanded into Watford City, ND creating McKenzie County Bank.
2006
Cornerstone Holding Company, Inc. begins with six Fargo based successful entrepreneurs purchasing Citizens State Bank in Enderlin, ND.
Cornerstone Bank opens in Fargo, ND.
2007
Cornerstone Bank opens in Bismarck, ND.
2008
The Petersen family acquires Peoples Bank in Makoti, Plaza, and Parshall, ND.
2014
Cornerstone Bank expands welcoming a team in Dickinson, ND.
December 31, 2014, Cornerstone Holding Company, Inc. and Lakeside Holding Company merge.
2016
March, the Dickinson team moves into their bank building located on 15th St W.
June, Cornerstone Bank further expands by welcoming a team in Sioux Falls, SD.
2018
December, the Sioux Falls team moves into their bank building located at the corner of 69th and Louise.
2019
August, Lakeside Insurance Agency, Inc. becomes Cornerstone Insurance Services, Inc.
2022
January, the Bismarck team moves into their new bank building located on N 12th St.
May, Cornerstone Bank further expands welcoming a team in Minot, ND.
October, Cornerstone Bank continues expansion welcoming a team in Rugby, ND.
2025
May, the Rugby team moves into their new bank building located at 235 Highway 2 SE.