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Alternate US 23, or ALT US 23, was a redesignation of a stretch of US 23 in Michigan from Monitor Township near Kawkawlin to about 4 miles south of Standish. In 1967, a stretch of what would later become part of the I-75 freeway was opened between the above 2 mentioned towns, and US 23 was designated on the new road. After the former US 23 was given the ALT US 23 designation, AASHTO, although it has no enforcement authority, did not approve of having two types of US 23's running parallel so close with each other, and after about a year, AL. US 23 became an extention of M-13. The freeway portion from I-75 to Kawkawlin became Connector M-13.