A rural post office established on Section 25-148-59 in 1882 with Isaac Mills as first Postmaster. N. C. Rukke is credited with establishing and naming it Ottawa, Minnesota. He was one of the first settlers in Pilot Mound Township, Griggs County or Greenwood Township as it was called then. He also was one of the first county commissioners. After a time Mrs. Peter Gunderson (Annie Koleen) became postmaster and it was then moved to the East of where Ottawa Church now stands. On the flat of the hill, North part of Section 31, Lenora Township, Griggs County. It was part dug out and pan sod house. This was where Annie Koleen homesteaded, also where they lived after she married Peter Gunderson. At the time the post office was in existence the Township was called Pleasant 1. This Ottawa Post Office was discontinued in 1892.

Source: Griggs County History 1879 - 1976 Page 361