The I-69 Thumb Region is the seven-county area of east-central Michigan — Genesee, Huron, Lapeer, Sanilac, Shiawassee, St. Clair, and Tuscola counties — that sits along and around the Interstate 69 corridor between Lansing and the Blue Water Bridge at Port Huron. The name comes from a regional economic development partnership that used this identity for years, and the label still appears in state planning documents, small-business programs, and grant paperwork.
This site is a plain-language reference for anyone trying to make sense of the region: which counties are in it, why I-69 matters to it, who actually maintains the roads, where the official data lives, and what organizations exist to help a small business or a community project here. Most of that information is scattered across state and federal agency sites; we pull it together and link you to the primary source every time.
Start with the county quick-reference table, which lays out all seven counties, their county seats, and the highways that serve them on one page. From there, the guides answer specific questions — what the region actually is, why I-69 is called a trade corridor, and where to get free help starting a business — without jargon and without guesswork.