The Ostrander branch of Security State Bank opened its doors on May 15, 1903. From 1903 until 1910, the Bank was located on the east side of Main Street in downtown Ostrander. A new building was constructed on the west side of Main Street and the Bank relocated to this site in 1910. In 1954, the current Bank building was constructed. Additional offices were added to this building in 1977-1978.

The organizers and original stock holders of the Bank were O.P. Hadland, H.O. Larson, and H.A. Skaarberg, all from Ostrander; C.M. Anderson from Preston, MN; and Theodore Wold of Winona, MN. These men also served as the Bank's first Board of Directors.

In 1988, all Bank stock (except five shares) was sold to Keith Bedford, John Waters, and Kevin Costley. In 1991, these owners sold their interest to the present owners, The Fischer Corporation of Lewiston, MN. This holding company also owned Security State Bank of Lewiston and First State Bank of Wykoff.

In 1993, Ostrander State Bank merged with First State Bank of Wykoff to become Security State Bank of Wykoff. In November of 1998, the Banks merged with the Lewiston office. Today the Banks are known as Security State Bank of Lewiston.