Michigan's 10th Congressional District is a border district. It is home to the Blue Water Bridge, which is the second-busiest border crossing on the northern tier; Selfridge Air National Guard Base, which has expanding missions in the area of homeland security; Coast Guard stations at Selfridge, Port Huron, and Harbor Beach; it borders Chemical Valley, which is one of the largest collections of petro-chemical operations in North America; the CN Rail Tunnel, which is the busiest rail artery in the U.S.; and is the genesis of important trade arteries, interstates I-94 and I-69.