St. Ansgar was founded in 1853 by a group of Norwegian immigrant farmers, led by the Rev. Claus L. Clausen a Danish minister. 

This town is named after a French monk and bishop, who in the 9th century was a missionary to the Scandinavian countries and was made the patron saint of Denmark. 

According to the 2010 Census, St. Ansgar experienced a 7.37% of growth in population from 2000 to increase our population from 1031 to 1107.  St. Ansgar had the highest population increase in all of Mitchell County.