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M-146 is a former state trunkline route existing from (c.)August 31, 1931 until (c)October 15, 1964.**
Southern Terminus*:	US-25/Military St (present-day BL I-94) in southern Port Huron, at the cnr of Conner St & Military St
Northern Terminus*:	US-25/M-51/Pine Grove Ave (present-day M-25) at the north end of the "Pine Grove Connector" in northern Port Huron
Final Length*:	5.504 miles
Maps:	Route Maps of Former M-146
Notes:	* The termini and final length of M-146 reflect the beginning and ending of the route and its length as of the time of its decommissioning in 1964.
	M-146, in its entire existence, was a bypass route for the City of Port Huron, although it had two different "lives" with the second "life" cut short by the arrival of the Interstate Highway System. Additionally, M-146 had a significant portion of its originally-established route go unbuilt, however later Port Huron bypass proposals would later incorporate that section, although those additional bypass routes would similarly go unconstructed.       While the portion of 24th St along the western limits of Port Huron, specificially the Dove St-to-Lapeer Ave segment, was established as a state trunkline route in 1924, that portion was apparently either an unsigned highway route or was incorporated into the route(s) of other state highway route(s). A 5.7-mile northerly extension of the proposed western bypass continuing northerly from 24th St at Lapeer Ave to the corner of 24th Ave & M-27/Pine Grove Ave, then northerly along 24th Ave to M-29/Lakeshore Rd approximately six miles north of downtown Port Huron was added in early 1930 to make the route a true bypass. US-25 was extended north from Port Huron along the Lake Huron shore to a new terminus at Port Austin at the tip of the Thumb in 1934, meaning the Port Huron West Belt would be a bypass for US-25 traffic from southwest of the city to north of the city (when completely constructed). It was also 1934 when the M-146 designation first showed up on official state highway maps distributed to the public on the existing portion of the route from US-25 in southern Port Huron to M-21/Lapeer Ave.       Then, in 1950, a new four lane, divided, limited-access route was announced to begin at M-21/Lapeer Ave just west of the 24th St route, then proceed northerly and northeasterly, crossing the Black River on a new bridge, then intersect with a westerly extension of the Blue Water Bridge approach roadway, then turn northerly to merge into US-25A/M-51/Pine Grove Ave north of Garfield St. This segment of highway is completed and opened to traffic in December 1954. A southerly extension of the divided limited-access highway to the south of M-21/Lapeer Ave to US-25/Gratiot Rd and on to M-29/Busha Hwy was then proposed to complete the bypass, with the existing M-146/24th St route serving to complete the bypass route until that time.       Soon after the new four-lane, divided, limited-access version of the M-146 West Belt opened, however, the Interstate Highway System came into being and the Chicago-Detroit-Port Huron route, eventually designated as I-94, was earmarked to terminate at the foot of the Blue Water Bridge in Port Huron. The State Highway Dept decided to incorporate the 5,000 foot (0.95 mile) portion of M-146 from the Blue Water Bridge approach southwesterly across the Black River bridge and through the Water St interchange into the route of the I-94/US-25 freeway and reconfigure the southerly turn in the existing route of M-146 toward M-21/Lapeer Ave so that the new I-94/US-25 freeway would continue farther to the west before making its southerly turn to bypass the Port Huron area, leaving the section of M-146 heading southerly to M-21/Lapeer Ave as a long, glorified freeway on- and off-ramp. In mid-October 1964, I-94/US-25 opened to traffic around Port Huron and M-146 was replaced by the I-94/US-25 designation from the "Lapeer Connector" northeasterly to the Blue Water Bridge approach where I-94 terminates and US-25 then replaced M-146 along the "Pine Grove Connector" northerly to US-25/Pine Grove Ave (formerly US-25A/M-51, modern-day M-25). The 24th St portion of M-146 from BUS US-25/Military St to M-21/Lapeer Ave was simultaneously cancelled as a state trunkline route. It's at this point the M-146 route markers are removed from the "Lapeer Connector," the only portion of the route remaining as a state trunkline and M-146 is relegated to history.
	**The advent of the M-149 route designation as well as the precise date of its decommissioning is, interestingly, rather difficult to pinpoint.       A large portion of the earliest segment of M-146 along 24th St on the western edge of Port Huron was established as a state trunkline route June 1, 1924, but all evidence points to this either being an unsigned trunkline route or officially part of another existing route for many years prior to being designated as M-146. In the early years of the state trunkline highway system, M-19 approached Port Huron from the southwest via Gratiot Rd/Military St, then departed from the area heading westerly, initially via Griswold St/Rd then later along Lapeer Ave/Rd. With the debut of the U.S. Highway System in the spring of 1927, many trunkline designation changes ocurred, including US-25 replacing M-19 from Detroit to Port Huron and M-21 being extended into Port Huron from Goodells along the former M-19 route. While internal State Highway Dept maps showed 24th St as a state trunkline route, it was unlabeled and all publicly-distributed maps clearly showed no trunkline or route designation along 24th St until 1932—nearly eight years after its establishment. (Other internal State Highway Dept maps indicate much of the 24th St route was constructed in 1927.) Oddly, starting in 1932 official maps show M-21 entering Port Huron via Lapeer Rd, but also depict it traveling along 24th St as well, meaning both Lapeer Ave and 24th St were both signed as legs of M-21, not a totally uncommon situation in the early days of the state highway system in Michigan. (Three-legged and multi-legged trunkline routes did exist in other areas in the 1920s and 1930s.) Two years later in 1934, M-146 shows up for the first time on official highway maps issued by the State Highway Dept with M-21 only shown along Lapeer Ave. Mentions of the M-146 designation do not appear in media reports until mid-1937! As many trunkline routes of this era were assigned route numbers sequentially as they were established, M-145 and M-147 were both established on August 31, 1931 indicating the M-146 designation was also like assigned at that same time, even if it was not immediately posted along the roadway.       At the end of its existence as a trunkline designation, M-146 seems to fade into history. The coming of the Interstate highway system and other freeways supplants the role of M-146 as Port Huron's "West Belt" bypass route and the 24th St portion of the route is cancelled as a trunkline route in mid-October 1964. However, while I-94 took over a portion of the limited-access M-146 "West Belt Line" route constructed in the mid-1950s (which also included a new Blue Water Bridge approach), the portion from southwest of Water St to M-21/Lapeer Ave was ultimately retained as a state trunkline route—essentially a long set of freeway off- and on-ramps connecting I-94 with Lapeer Ave. This is where the ambiguity comes in. The M-146 designation may have been officially retired with the decommissioning of the 24th St segment when I-94 was completed and opened traffic, but the "Lapeer Connector" still appeared on some maps marked as M-146 for some years. Eventually, the Lapeer Connector became internally designated within MDOT as the "Connector 9" sometime in the 1990s. These unsigned and unknown outside of MDOT connector designations were redesignated in the 2006–08 timeframe to make them more closely match one of the highways they connect with. As such, "Connector 9" became "Connector 69" as the northern end of the route terminated at I-94/I-69 at the same time as the nearby "Connector 13"—the limited-access connector from I-94/I-69 to M-25/Pine Grove Ave at the foot of the Blue Water Bridge—was designated as "Connector 25." So, since no specific evidence has been found as to exactly when M-146 was decommissioned as a state trunkline highway designation, the October 15, 1964 date will be used here for lack of a more concrete timeframe.
	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 just one change to the route of M-146 during that timeframe: Cancellation and transfer back to local control. The planners recommended transferring both the 24th St section between US-25/Military St and M-21/Lapeer Rd as well as what would become the "Lapeer Connector" portion from M-21/Lapeer Rd and the proposed I-94/US-25 freeway. The portions which would be incorporated into I-94/US-25 and the "Pine Grove Connector" would remain as trunklines, however. In the end, the 24th St segment was cancelled and transferred to local control four years later, while the same was originally intended for the "Lapeer Connector," it was ultimately retained in the trunkline system and survives to this day as unsigned "Connector 25."
History:	1924 (July 1) – A 12.0-mile segment of state trunkline is established in St Clair Co beginning on the western limits of Port Huron at 24th & Dove Sts and continuing northerly along 24th St, then westerly for approximately 1.8 miles, then westerly along Lapeer Rd through Wadhams to Goodells Rd north of Goodells. This portion of trunkline seems to have been established as part of M-19, although all publicly-available maps show M-19 as departing Port Huron to the west via Griswold Rd instead of Lapeer Ave (this is likely the signed "marked-and-maintained" route at this point).
	1930 (Dec 2) – A 5.7-mile northerly extension of the Port Huron "bypass" route is established, beginning at Lapeer Ave & 24th St and continuing northerly, with a slight bend to the west to avoid a bend in the Black River before heading northerly again to the corner of 24th Ave & M-27/Pine Grove Ave, then northerly along 24th Ave to M-29/Lakeshore Rd approximately six miles north of downtown Port Huron. The portion of the newly-established route from M-21/Lapeer Rd to M-27/Pine Grove Ave remains unconstructed, while the segment along 24th Ave from M-27/Pine Grove Ave to M-29/Lake Shore Rd is a county road not yet brought up to trunkline standards.
	1931 (May 19) – Act 131 of 1931—the Dykstra Act—is passed allowing the State Highway Dept to take over control of state highways running into and through incorporated cities, thereby officially incorporating them as state trunkline highways. Up to this point, the 0.8-mile segment of 24th St from Dove St southerly to US-25/M-29/Military St in southern Port Huron is officially established as a state trunkline route.
	1939 (Nov 15) – The northernmost 2.6-mile segment of the trunkline route established in December 1930 as part of the proposed northerly extension of the M-146 Port Huron bypass, from M-51/Pine Grove Ave to US-25/Lakeshore Rd, is completed and opened to traffic. However, this segment is designated as US-25A (US-25 Alternate) and the US-25A designation is extended southeasterly along M-51/Pine Grove Ave to connect back with US-25 in Port Huron at the cnr of Pine Grove Ave & Stone St. At this point, the Port Huron bypass is discontinuous, exisitng as M-146 along 24th St south of M-21/Lapeer Ave and as part of US-25 along 24th Ave north of M-51/Pine Grove Ave. State Highway Dept officials state planning the completion of the bypass, including a possible lift bridge over the Black River, is underway and are hopeful construction will begin by 1941.
	1950 (Feb) – While the original plan had been to construct a direct connection between M-146/24th St (south of M-21/Lapeer Ave) and US-25A/24th Ave (north of Pine Grove Ave) to complete the Port Huron West Belt bypass, after postponement due to World War II, the State Highway Dept comes up with an alternate plan to build a limited-access, four-lane divided highway from M-21/Lapeer Ave northerly and northeasterly across the Black River to an extended Blue Water Bridge approach, then turning northerly to merge into US-25A/M-51/Pine Grove Ave north of Garfield St.
	1954 (Dec 6) – Although originally expected to open to traffic on October 30, the four lane, divided, limited-access M-146 West Belt bypass opens to traffic from M-21/Lapeer Ave northeasterly across the Black River, intersecting with the Blue Water Bridge approach extension, then northerly merging into US-25A/M-51/Pine Grove Ave (present-day M-25) north of Garfield St. The intersection with Water St is a fully grade-separated freeway-style diamond interchange. Oddly, it would be 2½ years before this 2.669-mile section of highway would be officially established as a state trunkline highway route. M-146 is concurretnly designated along the short section of M-21/Lapeer Ave to connect the 24th St route with the new West Belt highway.
	1957 (June 24) – The 2.669-mile segment of the M-146 Port Huron West Belt which was opened in early December 1954 is finally established as a state trunkline route from M-21/Lapeer Ave to US-25A/M-51/Pine Grove Ave (present-day M-25). At the same time, the unbuilt 3.0-mile long proposed M-146 West Belt segment between M-21/Lapeer Ave and US-25A/M-51/Pine Grove Ave is cancelled as a state trunkline route and will go forever unconstructed.
	1964 (Oct 14) – A 7½-mile long segment of I-94/US-25 freeway is completed and opened to traffic from the end of the existing freeway at US-25/Gratiot Rd (present-day Exit 266) near Marysville northerly around Port Huron to the Lapeer Connector (formerly signed as M-146), part of the Port Huron West Belt and approach to the Blue Water Bridge. From there, I-94/US-25 replaces M-146 as the designation along the freeway leading across the Black River to the foot of the Blue Water Bridge. The former route of US-25 through Marysville and Port Huron is redesignated at BUS US-25, with the "Pine Grove Connector" portion of the former M-146/Port Huron West Belt now bearing the US-25 mainline route designation. The remaining portion of the West Belt not incorporated into the routes of I-94 or US-25—the "Lapeer Connector" leading from I-94/US-25 southerly to M-21/Lapeer Rd—likely has its M-146 markers also removed and becomes an unsigned state trunkline route at this point.
	1965 (May 26) – The State Highway Dept informs the Port Huron City Commission that it intends to retain control over the portion of (former?) M-146 from existing M-21/Lapeer Rd northerly to I-94 instead of turning the portion of the route back to local control, as was originally planned.
Controlled Access:	At the end of its existence, all of M-146 from M-21/Lapeer Rd northerly to US-25/M-51/Pine Grove Ave (present-day M-25) was a combination of freeway and expressway, with some at-grade in the southernmost and northernmost portions of this section.
Photographs:
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