Complex sentence: The original Shore Trail ran roughly parallel to the route of the modern US 23 from the Bay City area to Cheboygan; another section followed the Saginaw Trail between Flint and Saginaw.
Split into simpler sentences: The original Shore Trail ran roughly parallel to the route of the modern US 23 from the Bay City area to Cheboygan. Another section of the current highway follows the Saginaw Trail between Flint and Saginaw.