Borings (5 of 7)

Concrete borings; No.  17-G21 0 ft to 28 ft and No.  17-G21 28 ft to 55.8 ft., Electronic reproduction of photograph.  The Mackinac Bridge 1954 - 1958. Mackinac Bridge Authority
Abstract/Description: Concrete borings; No. 17-G21 0 ft to 28 ft and No. 17-G21 28 ft to 55.8 ft.
Subject(s): Bridges--Design and construction
St. Ignace (Mich.)
Mackinaw City (Mich.)
Mackinac Bridge (Mich.)
Date Created: 1955 (approximate)