Answer: markets all around the world
Step-by-step explanation:
The Great Lakes provides access to Midwestern farmers to markets all over the world because each lake is linked and eventually empties into the Atlantic ocean. Midwestern farmers are therefore able to ship their goods via the great lakes, to the Atlantic, to anywhere in the world.
This enabled the growth of heavy industry and other economic sectors in the area as the people took advantage of the logistical advantages offered by the Great Lakes.