Great Northern Railway Historical Society Blueprint Collection JSBP1285, Duluth, Minnesota, 1923. Northern Pacific Railroad Blueprint Number Sheet 1 AND 2, Np Field Completion Report. Viaduct at 9th Avenue West. Authorization for Expenditure 1664-23. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1286, Duluth, Minnesota, 1923. Great Northern Blueprint Number SKETCH # 235.03, Ninth Avenue Viaduct. Sketch Showing Jct of Timber Ramp and Concrete Roadway. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1287, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-4, Viaduct at 9th Avenue West. General Arrangement of Viaduct. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1288, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-6, Viaduct at 9th Avenue West. Detail of Girder Supports and Columns for Viaduct. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1289, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-7, Viaduct at 9th Avenue West. Wind Bracing Details. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1290, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-14, Viaduct at 9th Avenue West. Track Girders Across Ramps. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1291, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-12, Viaduct at 9th Avenue West. Detail of Viaduct at Michigan Street. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1292, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-1, Viaduct at 9th Avenue West. Timber Approach to Driveway at 3rd Floor Elevation. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1293, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-11, Viaduct at 9th Avenue West. Concrete Bents Fo Viaduct. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.

Great Northern Railway Historical Society Blueprint Collection JSBP1294, Duluth, Minnesota, 1923. Great Northern Blueprint Number 235-2, Viaduct at 9th Avenue West. Detail for Timber Approach to Driveway at 3rd Floor Elevation. Interstate Commerce Commission Account Number 6, Bridges, Trestles, and Culverts. Other ICC account descriptions: ICC Account Number 6, Bridge.