This four-volume set of photo albums has a printed title page that reads Historical Markers in Minnesota. The albums were compiled circa 1942 under the direction of Harold E. Olson, who served as head of the Roadside Development Division from 1932
to 1963. They were updated circa 1954 while Olson was still head of the division.
Volumes 1 through 3 of the Olson albums depict roadside development properties arranged numerically by S.P. number. Volume 4 contains only state line markers, which are monuments that were erected in the 1 930s and 1940s at major trunk highway entrance points to welcome travelers into Minnesota. The contents of the volumes are listed below:
Volume 1 - S.P. 0000-2699
Volume 2 - S.P. 2700-6899
Volume 3 - S.P. 6900-8199
Volume 4 - State Line Markers
