Ready to build, buy or expand your business? St. Clair County, Michigan, offers many great reasons to make your short list and become your premiere choice for doing business. Excellent transportation by car, bus, water, air or rail. International Border Crossing. Located within 500 miles of 1/2 the U.S. population. Access to the Great Lakes shipping lanes. Two class I railroads (doublestack capacity). Small town charm with close proximity to major metropolitan markets for business & recreation. Interstates I-94, I-69 and Highway 402 (Canada). Cross the Blue Water Bridges to Canada/U.S. in just minutes!