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Western Terminus:    Updated M-37 (cnr East Beltline Ave & Fulton St) on the east side of Grand Rapids
Eastern Terminus:    I-475/UAW Frwy at Exit 7 in downtown Flint
Length: Updated 99.967 miles
Map: Route Map of M-21
Notes: Prior to the coming of the Interstates, M-21 was a key "Coast-to-Coast" highway in the Lower Peninsula, stretching from Holland on Lake Michigan to Port Huron on Lake Huron, passing through Grand Rapids and Flint en route. After the main north-south "Grand Rapids Expwy" (US-131) was nearing completion through that city, an east-west freeway was proposed with the designation M-21. While the M-21 designation did grace that freeway for a time, it was—and is—more principally known as I-196. The first leg of M-21 to be severed was the Holland-to-Grand Rapids portion, replaced by a completed I-196 freeway in the mid-1970s (with much of the former route re-designated as M-121 in 2007). The next, and bigger, leg to be severed was the Flint-to-Port Huron segment, replaced by I-69 a decade later. Since that time, no major changes to this once-key route have taken place.
  New! In "State Trunkline Needs, 1960–1980," a set of maps prepared by the State Highway Dept's Office of Planning, Programming Division in 1960 showing possible additions, upgrades and improvements to the state trunkline system over the ensuing twenty years, MSHD staff recommended a massive upgrade to the route of M-21 during that timeframe. While looking back, it's clear the planners were overly ambitious, at the time freeway-building had yet to reach its zenith. In these maps, M-21 was reccommended to be upgraded to a full freeway beginning at the I-96 & I-196 junction east of Grand Rapids, continuing easterly bypass Ada, Lowell, and Saranac to the north, and Ionia, Lyons, Muir, Pewamo, Fowler, St. Johns, Ovid, Owosso, and Corunna to the south, before merging back into its existing alignment at M-13. The existing M-21 along Corunna Rd between M-13 and Linden Rd would be converted to freeway, with the freeway then angling southeasterly to an interchange with I-75/US-10/US-23 in the vicinity of the Miller Rd interchange. Under these planas, M-21 would then transition to what is now I-69 (which was largely built as the M-21 freeway from the 1960s to the 1980s) from Flint to Port Huron, featuring proposed BUS M-21 routings at Flint, Lapeer and Imlay City (none of which were ever designated).
History: 1920 M-21 begins at the jct of M-16 & M-44 in South Ionia (present-day cnr of M-66/State Rd & Riverside Dr) and continues easterly along the south side of the Grand River through Lyons to Pewamo. From there, M-21 continues along its present-day route through St Johns to Ovid, where it diverges slightly from its present alignment to travel along Simpson Rd to Five Points, then continues easterly into Owosso. There, M-21 bends southerly travelling through downtown Corunna and continues into Lennon along Lytle Rd. From Lennon, M-21 then continues easterly along its present route into downtown Flint. Between Flint and Goodells, M-21 travels roughly along its pre-1980s routing through Lapeer, Imlay City and Emmett. M-21 ends at M-19 in Goodells.
  1922 By 1922, M-21 is extended easterly concurrently with M-19 from Goodells into downtown Port Huron.
  1926 With the debut of the US Highway system, M-21 is extended on the west concurrently with US-16 (formerly M-16) into downtown Grand Rapids, then southwesterly via Hudsonville to Holland, replacing the M-51 designation along Chicago Dr. This adds about 33 miles to the length of M-21. Also, on the east, the concurrent M-19/M-21 designation becomes just M-21 from Goodells into Port Huron when M-19 is realigned to run south from Yale to Richmond.
  c.1927–28 In this timeframe, M-21 is realigned between Grand Rapids and Ada, running along Fulton Ave between those communities, north of its previous alignment. The portion of the former M-21 between US-16 and Ada is turned back to local control. M-21 is also realigned to run along the north side of the Grand River between Lowell and Saranac, with the former route along the south side of the river being turned back to local control. In addition, the routing of M-21 between Ovid and Five Points (west of Owosso) is straightened and placed onto its modern-day alignment. The former route is, again, turned back to local control.
  1929 M-21 is realigned between Flint and Lapeer. Beginning at the cnr of Court St & Lapeer Rd in Flint, M-21 now continues easterly along Court St to US-10/Dort Hwy, jogging northerly with US-10 to Davison Rd, then easterly along Davison Rd through Davison, merging with the old route just west of Lapeer. The former route along Lapeer Rd from Court St in Flint to M-15/State Rd south of Davison was redesignated as M-21A. From M-15 easterly to Davison Rd at Lapeer, the former route is turned back to local control.
  1929 (Aug 26) A more direct trunkline alignment between Holland and Zeeland is completed and officially determined as a state trunkline, designated M-21, running via Chicago Dr directly between the two cities. The former route via Eighth St and Holland-Zeeland Rd (present-day Paw Paw Dr) is turned back to local control on this day. Also at this time, a new route for M-21 through Zeeland is put into service with the inclusion of Washington Ave from W Main Ave on the western edge of the city easterly to Colonial St in the state trunkline system. Between Colonial & Carlton Sts, Washington Ave is signed as M-21 but is a locally-maintained street.
  1930 About 8 miles of M-21 is realigned to the north side of the Grand River in Ionia Co, from Saranac to the east side of Ionia, crossing the Grand at Cleveland St and back to its original route there. The former route between Saranac and Ionia is turned back to local control.
  1931 The Dykstra Act this year allows the State Highway Dept to actually maintain state trunkline facilities through cities. The portions of M-21 within cities along its route are transferred to state control.
  c.1931-32 The final 11 miles of M-21 in Ionia Co to be moved to the north side of the Grand River is completed, running along its present-day alignment from Ionia to Pewamo. The former route on the south side of the river is turned back to local control. Also, in Lapeer Co, M-21 is moved onto its "classic" routing between Lapeer and Imlay City along Imlay City Rd. Previously, M-21 ran through downtown Lapeer, then easterly along Bowers Rd to Lake Pleasant Rd, southerly on Lake Pleasant to Attica Rd, then easterly on Attica Rd (4th St in Imlay City) to M-53. This route is turned back to local control. In yet another realignment in St Clair Co, M-21 is transferred onto its "classic" alignment there along Lapeer Rd from near Goodells via Wadhams and into downtown Port Huron. The former route, along Goodells, Sparling and Griswold Rds, is turned back to local control. In all, these changes also signified the completion of hard-surfacing to all of M-21 from coast-to-coast.
  1932 (Oct 29) Carlton St in Zeeland from Main Ave northerly to M-21/Washington Ave, no longer a signed portion of M-21 since August 1929, is finally transferred to local control.
  1933 A 3-mile, gravel-surfaced bypass of Pewamo opens (thus reversing the completed paving of M-21 just a year or two earlier!). The bypass is completely hard-surfaced within a year, however. The former route of M-21 through Pewamo is designated M-210. (In more modern times, M-210 would have been designated BUS M-21 instead.)
  1939 In early-1939, the former M-21 (redesignated as M-210) through Pewamo is removed and turned back to local control.
  1944 A new BYP (Bypass) M-21 is created in the Grand Rapids area, beginning at jct M-21 & BYP US-16 (cnr 28th St & Chicago Dr) in Grandville, running easterly with BYP US-16 and BYP US-131 along 28th St to East Beltline Ave, then northerly with BYP US-131 along East Beltline Ave back to M-21/E Fulton St east of Grand Rapids.
  1948 All of M-21A from Flint to Davison is "decommissioned" as a state trunkline and turned back to local control.
  1950 The highway is realigned at Capac to remove two sharp 90-degree turns.
  1952 In mid-1952, the highway is realigned at Emmett to remove two more sharp 90-degree turns.
  1953 (Summer) M-21 is rerouted in the Grand Rapids area to replace the BYP M-21 designation created nearly a decade earlier along 28th St and East Beltline Ave. The former route of M-21 through Grand Rapids (along Chicago Dr, Grandville Ave, Franklin St, Eastern Ave and Fulton Ave) is re-designated as BUS M-21.
  1954 With the completion of the new US-31 bypass of Holland, M-21 between the new bypass and downtown is co-signed with a new BUS US-31 designation (and is not truncated at the bypass as previously believed). Why M-21 is not truncated at US-31 is not clear.
  1956 (Early Dec) New! A southerly, limited-access bypass (access only at intersecting crossroads—no private driveways) of the City of Zeeland is completed and opened to traffic, a few weeks before the projected completion date of December 31. The new bypass begins northeast of downtown and departs the former route of M-21 just west of 80th Ave bending southwesterly (via present-day M-121/Chicago Dr) to Main Ave then bending westerly to bypass the city to the south before merging back into Chicago Dr southwest of the city west of 112th Ave. Although not yet officially determined as a state trunkline route, M-21 is transferred to the new bypass, while the former route through Zeeland via Washington Ave and Chicago Dr is retained as an unsigned state trunkline route for the time being.
  1957 (Oct 21) New! A new $670,000 four-lane bridge spanning the Grand River at Ada in central Kent Co is completed and opened to traffic, just upstream from the existing M-21/Fulton St bridge across the river. The old bridge is to be demolished. The western approach to the former bridge is converted into a boat launch access roadway, while the former route of M-21 from the eastern approach (at Honey Creek Ave) southeasterly to the eastern approach to the new bridge is turned back to county control and becomes an extension of Pettis Ave.
  1958 (Mar 6) Updated The Zeeland Bypass is officially assumed into the state trunkline system, although it has been open to traffic for approximately 15 months at this point. At this same time, the former route of M-21 through Zeeland via Chicago Dr and Washington Ave is also officially turned back to local control.
  1964 With the completion of the new I-196 freeway through Grand Rapids from I-96 east of town to Chicago Dr in Grandville, M-21 is rerouted to follow I-96 westerly (from present-day Exit 39) to I-196, then westerly along I-196 through Grand Rapids, then back onto its original routing (Chicago Dr). BUS M-21 is slightly extended at each end: from 28th St to the new I-196/M-21 freeway along Chicago Dr in Grandville; and from East Beltline Ave (M-44) to M-21 at I-96. The former M-21 routing along 28th St becomes a part of M-11, while the routing along East Beltline Ave becomes a part of M-44.
  1966 (Oct 19) Updated M-21 is rerouted onto a newly-constructed freeway from the Wadhams area into downtown Port Huron, which is opened to traffic on this date. The former route of M-21 (Lapeer Rd) is turned back to local control.
  1968 (Oct 18) New! The 21.39 miles of the east-west freeway through the Greater Flint area from M-121/Bristol Rd east of Swartz Creek easterly through Flint and past Davison to the Genesee/Lapeer Co line and the 7.16-mile portion from the Genesee/Lapeer Co line easterly to M-24 south of Lapeer is officially determined as a state trunkline route. The western portion of this route is scheduled to be part of M-78 while the eastern portion is to become M-21.
  1971 (Aug 16, 11:30 am) Updated – The 16-mile portion of the M-21 freeway from Center Rd in Burton in Genesee Co easterly to M-24/Lapeer Rd south of Lapeer in Lapeer Co is completed and opened to traffic. The former route of M-21 along Davison Rd (Flint St in Davison) remains an unsigned state trunkline route for the time being.
  1971 (Dec 1) Updated The 1.35-mile portion of former M-21 within the City of Lapeer from the west city limit at Millville Rd easterly to M-24/Main St is turned back to city control. This comes 3½ months after the M-21 freeway is opened from M-24 westerly just south of Lapeer.
  1971 (Dec 21) Updated The 2.5-mile segment of the M-21/M-78 freeway through downtown Flint from the eastern end of the M-78 freeway at BUS M-54/Saginaw St easterly to the western end of the M-21 freeway (opened to traffic four months earlier) is opened to traffic. This completes the east-west freeway through the Greater Flint area. While sources show the freeway east of Flint toward Davison was to have possibly borne the M-78 designation, at this point M-78's eastern terminus is fixed at the future I-475 interchange in downtown Flint with M-21 continuing easterly on its own past Davison and toward Lapeer. West of Flint, M-21 is rerouted at M-13, heading southerly with M-13 through Lennon to the M-78 freeway, then easterly concurrently with M-78 into downtown Flint and on toward Lapeer. The former route of M-21 along Corunna Rd, Miller Rd and Court St between M-13 at Lennon and BUS M-54/Saginaw St in downtown Flint is redesignated as M-56.
  1972 (June 9, Sept 22) New! The former route of M-21 along Davison Rd from Center Rd easterly to the western Davison city limit and from the eastern Davison city limit easterly to Genesee/Lapeer Co line is turned back to county control on June 9. Then on Sept 22, the 1.439 mile portion of former M-21 along E Court St from future I-475 and M-54/Dort Hwy, the one mile of former M-21 along Davison Rd in Flint from M-54/Dort Hwy to Center Rd and the one mile along Flint St in the City of Davison are both turned back to city control. Also on Sept 22, the 6.1 miles of former M-21 from the Genesee/Lapeer Co line easterly to the western Lapeer city limit at Millville Rd is turned back to county control.
  1972 BUS M-21 in Grand Rapids is sliced in half, with the portion to the east of US-131 along Franklin St and Eastern Ave & Fulton St is removed and turned back to municipal control. The remaining portion of BUS M-21 between Grandville and US-131 becomes a "spur" business routing.
  1973 The M-78 designation is removed from the portion of M-21 freeway concurrently designated with M-78 between M-13 at Lennon and downtown Flint and replaced by the newly-extended I-69 designation from Charlotte.
  1974 Approximately 34 miles of M-21 are lopped off the western end with the completion of I-196 between Holland and Grandville. The former route from US-31 at Holland to east of Zeeland becomes a part of a new BL I-196. The portion of Chicago Dr (Old M-21) from Zeeland to I-196 at Grandville becomes an unsigned state trunkline (then M-121 in 2007). The former BUS M-21 between I-196 and the Grandville/Wyoming city limit is turned back to local control, while the remaining portion of BUS M-21 from that point to US-131 becomes a new BS I-196. M-21 proper is extended westerly from I-96 at Exit 39 to end at M-37/M-44/East Beltline.
  1983 The first segment of the new M-21 freeway opens from M-19 at Emmett to the existing M-21 freeway west of Wadhams (west of Port Huron). The former route of M-21 between M-19 and Taylor Rd becomes an unsigned state trunkline. The remaining gap from M-24 at Lapeer to M-19 at Emmet is under construction as the M-21 freeway.
  1984 (Dec 14) The entire freeway from Lapeer to Wadhams opens, not as M-21, but rather as an easterly extension of I-69. The length of M-21 is reduced by approximately 70 miles to end in Flint. Firstly, the M-56 designation which had replaced M-21 along Corunna & Miller Rds and Court St between M-13 and I-475/UAW Frwy in downtown Flint is re-designated as M-21. (M-56 ceases to exist as a state highway designation). The former M-13/M-21 through Lennon reverts back to just M-13, while the concurrently-designated M-21/I-69 between Lennon and Flint becomes just I-69. Between Flint and Port Huron the highway, including the M-21 freeway segments (I-475-to-M-24 and M-19-to-I-94) becomes I-69. The former route along Imlay City Rd from Lapeer to the Lapeer/St Clair Co line is turned back to local control, while the remainder in St Clair Co to Emmet becomes an unsigned state trunkline. The former M-21 into downtown Port Huron along the Griswold-Oak Sts pair is designated as BS I-69, ending at M-21's former terminus at M-25/Huron Ave.
  2003 The 9.34 miles of unsigned OLD M-21 in St Clair Co, from M-19 at Emmett easterly to Taylor Rd, is turned back to county control.
  2005 (Mar 3) – The last 12.1 miles of unsigned OLD M-21 in St Clair Co, from the Lapeer Co line easterly to M-19 at Emmet, is transferred to county control.
Controlled Access: No portion of M-19 is freeway or expressway.
NHS: M-21 is part of the National Highway System (NHS) in two different segments:
  • In Kent Co, from the western terminus of M-21 at M-37/M-44/East Beltline Ave easterly to Ada Dr in Ada. (5.5 miles) (This segment was added in 2012 with the passage of the MAP-21 funding and authorization bill.)
  • From the Elms Rd west of Flint to M-21's eastern terminus at I-475/UAW Frwy in downtown Flint. (6.9 miles) (The segments of M-21 from Elms Rd to I-75/US-23 and from Saginaw St to I-475 were added in 2012 with the passage of the MAP-21 funding and authorization bill.)
Memorial Highways:  New! The following Memorial Highway designations have been officially assigned to parts of M-21 by the Michigan Legislature:
  • PFC Harold R. Cooley WWII Marine Corps League Memorial Highway – "The portion of highway M-21 in Shiawassee County beginning at the intersection of M-21 and Meridian Road and continuing east to the intersection of M-21 and M-13..." From MDOT: "The Harold R. Cooley Detachment of the Marine Corps League is based in Shiawassee County and honors an Owosso marine killed in the reconquest of Guam in 1944.)"
  • Mark V. Ingram II Freeway – "Highway M-21 beginning at the intersection of M-21 and I-75 in Genesee county and continuing east to the intersection of M-21 and I-475..." From MDOT: "Mark V. Ingram II is a former running back for the University of Alabama, where he won the 2009 Heisman Trophy. He grew up in Flint, Michigan, and attended high school at Southwestern Academy, where he was ranked as the 17th best athlete in the nation and the 6th best athlete in Michigan by Rivals.com, according to information on the University of Alabama website. Ingram received a number of honors and awards after the Alabama Crimson Tide won its 13th National Football Championship in 2009." Note: Oddly enough, at no point anywhere, especially between I-75/US-23 and I-475 in Flint, is M-21 a freeway, so why this highway is named "Freeway" is quite odd, indeed.
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