Michigan Highways: Since 1997.

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M-22 & M-109 junction route signage in Glen Arbor, Michigan
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Former M-2
M-3 Route Marker On to Next Route:
Former M-4
Southern Terminus:   Updated 2023-04 Cnr Gratiot Ave & Randolph St in downtown Detroit.
Northern Terminus:   Jct I-94 & M-29 at Exit 243 in Chesterfield Twp west of New Baltimore.
Length: Updated 2023-04 26.668 miles
Map: Route Map of M-3
Notes: Known as Gratiot Ave for most of its length. Before 1972, this route was a portion of US-25 in Michigan.
  Until 1998, the northernmost 3½ miles of M-3 were concurrently designated with M-59. However, with the completion of the M-59/Hall Rd upgrade, the M-59 designation was transferred from Gratiot Ave & 23 Mile Rd onto the portion of Hall Rd east of Gratiot to I-94. Gratiot and 23 Mile Rd north of Hall Rd is now designated only as M-3.
History: 1974 (Winter) Updated 2023-04 – After only 47 years of existence, MDOT working in conjunction with ODOT in Ohio asks AASHTO and receives permission to completely decommission US-25 in both states. The highway has been largely replaced by I-75 throughout Ohio and into Michigan as far as downtown Detroit. From there northeasterly to Port Huron, US-25 has been functionally replaced by I-94, leaving only the stretch from Port Huron to Port Austin unduplicated. The segment of US-25 from I-75 at Exit 47 west of downtown Detroit through downtown and then northeasterly to I-94 at Exit 243 in Chesterfield Twp west of New Baltimore is redesignated as M-3.
  1981 (Jan 28) - The former route of Sbd M-3 through downtown Mount Clemens via Welts Ave and Gratiot Ave (from Welts southerly to halfway between Robertson & Kibbee Sts) is turned back to local control after a new westerly bypass of the downtown district is completed. Sources indicate the new relocation of Sbd M-3 opened the previous year, however. The former route of Sbd M-3 along Gratiot Ave is also renamed Main St by the City of Mount Clemens.
  1998 - The final portion of the M-59 upgrade is completed and the concurrent M-59 designation is removed from M-3 north of Hall Rd, leaving the M-3 designation as the sole route number there.
  2001 (Mar 15) - During a spate of jurisdictional transfers in the City of Detroit, which included several former state trunklines in the Campus Martius area of downtown being transferred back to City of Detroit control, M-3 is actually severed into two discontinuous portions. The two blocks of Cadillac Sq from Woodward Ave to Randolph St designated as part of M-3, as well as Fort St between Woodward and Griswold St, are transferred to the City of Detroit. (Please see the jurisdictional transfer maps linked under "Weblinks" below.) This leaves two issues, solved thusly:
  • The discontinuous segment of M-3 along Fort St from Griswold St westerly to Clark St, then northerly on Clark St to the I-75/Fisher Frwy is redesignated as part of M-85. This is possible as MDOT also assumes control of Fort St from Clark St southwesterly to the former northern terminus of M-85. The one block stretch of former M-3 from Fort St to I-75 is an unsigned state trunkline connector.
  • Since M-3 has been truncated to the cnr of Cadillac Sq & Randolph St and since Randolph St from Cadillac Sq southerly to M-10/BS I-375/Jefferson Ave is an unsigned state trunkline connector, the M-3 designation is simply extended southerly via Randolph to end at Jefferson.
  2023 (Apr 26) New! 2023-04 – The southernmost 0.396 mile of M-3—the segment along Randolph St from Jefferson Ave (at jct M-10 & BS I-375) northerly to Gratiot Ave—is transferred to the City of Detroit in addition to the payment of $7,609,203.68, with the payment being made in lieu of MDOT completing a reconstruction project which had been originally been programed. The City of Detroit will be responsible for completing the project within five years or the payment needs to be returned to MDOT. This jurisdictional transfer creates the fifth trunkline "spur" with a terminus at a random downtown Detroit street as opposed to at some other trunkline or natural feature. (M-85 terminates at Griswold St, US-12 and M-5 both end at their respective intersections with Cass Ave, while M-1 ends at Adams St—see Downtown Detroit Trunklines Map.) Prior to this transfer, M-3 had been 27.064 miles in length.
Controlled-Access: No portion of M-3 is freeway or expressway.
NHS: Updated The entire length of M-3 is part of the National Highway System (NHS). (The segment of M-3 from its southern terminus at BS I-375/Jefferson Ave and the I-75 connector ramps northeast of downtown was added in 2012 with the passage of the MAP-21 funding and authorization bill.)
Memorial Highway:  New! The following Memorial Highway designation has been officially assigned to part of M-3 by the Michigan Legislature:
  • Ronald W. Reagan Memorial Highway – "Highway M-3 in Macomb County beginning at the intersection of M-3 and Harrington Boulevard and continuing north to its end..." From MDOT: "Born in Tampico, Illinois, on February 6, 1911, Ronald Reagan initially chose a career in entertainment, appearing in more than 50 films. While in Hollywood, he worked as president of the Screen Actor's Guild and met his future wife, Nancy (Davis) Reagan. He later served two terms as governor of California. Originally a liberal Democrat, Reagan ran for the U.S. presidency as a Republican and won two terms, beginning in 1980, ultimately becoming a conservative icon over the ensuing decades. Having suffered from Alzheimer's disease in his later years, Reagan died on June 5, 2004."
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