Here is a chart that shows how many interpreters are registered in the state of Michigan. The information comes from the public interpreter directory published by the Division on Deafness, DeafBlind and Hard of Hearing. You may mouse over the graph to see specific numbers.
Key: Blue: All interpreters. Orange: Nationally Certified Interpreters. Green: EIPA K12 Interpreters. Red: State Qualified Interpreters. Interpreter information comes from the Division on Deafness, DeafBlind and Hard of Hearing (2016)
One issue that Michigan deals with is area-specific shortages. For example, there are few interpreters in the UP and Northern Michigan. Most interpreters in the state seem to be clustered near Kalamazoo, Lansing, and Detroit. In Lansing there is a college (Lansing Community College) that produces a sizable number of ASL interpreters for the state. Detroit has a large concentration of Deaf adults. Notice there are large areas in northern Michigan and in the Upper Peninsula that have zero registered interpreters—these areas are served by interpreters traveling from other locations.
Interpreter information comes from the Division on Deafness, DeafBlind and Hard of Hearing (August 2015). Population information from US Census Bureau (2015)