developed the system of road construction called
"macadamize," in which the road bed is raised
slightly above the level of the surrounding land,
drainage ditches edge each side, and the road itself
consists of layers of stones that became compressed into
a solid surface by repeated traffic.
Located in Chicago, Illinois, Calumet
Skyway is an 8-mile-long toll road that connects with the
Indiana Toll Road. Opened in April 1958, the $101 million
elevated highway has six traffic lanes.