This map also comes from the “Master Plan for Ford Properties” created in 1970. Ford recognized the importance of Detroit as a hub for goods and the need to adequate transportation. Here is an explanatory excerpt:

Historically, Detroit owes its existence and its importance to water transport and a plentiful supply of natural resources. Its modern growth has been largely dependent upon manufacturing, especially manufacturing associated with many different means of transportation.

The Pullman car works were first established there and continued in operation until 1893. The first freight car works were established in 1853. In 1902 these two industries employed employed 7,200 men.

Detroit’s geographical situation led to the construction of small and large vessels for lake traffic, which commenced in 1852 and has continued to the present day. […]