A relative late-comer in terms of U.S. Highways in Michigan, US-33 was never a very long highway and, while it came close, never even left Berrien County. It entered Michigan from the South Bend, Indiana area and ran through downtown Niles and Berrien Springs before heading to St Joseph where the highway ended for many years. Later, it was extended to the northernmost portion of Berrien County before eventually being scaled back significantly then decommissioned in the state altogether.
As noted above, US-33 only ran a short distance in Michigan, never leaving Berrien County and never longer than approximately 35 miles. While longer than the tiny portion of US-8 in the Upper Peninsula, this highway was also concurrently signed with other routes for much of is existence. In fact, it remains unclear why US-33 was designated in Michigan in the first place! Also interesting to note, every mile of of what had been designated US-33 is still a state trunkline to this day, so decommissioning was not due to a transfer of any segment of roadway to local control.
US-33 debuted in Michigan in the late-1930s, almost a decade after the rest of the U.S. Highway system was created and signed. It was created as an "angling" highway running from Virginia northwesterly through West Virginia, Ohio and Indiana, then into Michigan. US-33 replaced the existing Indiana SR-2 from Fort Wayne to Elkhart, then westerly into South Bend to US-31. At this point, South Bend, Indiana would have made a perfectly logical terminus for the highway. However, for some reason, transportation officials continued US-33 northerly from South Bend via the existing US-31 through Niles, ending in downtown St. Joseph. It could be assumed officials felt Lake Michigan to be a more desirable terminus instead of South Bend, although that hypothesis is purely conjecture.
For nearly 25 years, US-33 ran concurrently with US-31 for its entire length in Michigan, from the state line between South Bend and Niles to its northern terminus in downtown St. Joseph. Only with the coming of the Interstate highway system was US-33 destined to be signed on its own. In the early-1960s, US-33 was extended northerly along US-31 to northernmost Berrien County to take over the route for when US-31 is moved over onto the new freeway bypass of the Benton Harbor area. Thus, US-33 is routed solo for the first time in its history in Michigan, although that was not the original intent. When US-31 was first relocated to the I-94 and I-96 (now I-196), the route of US-33 through St Joseph was initially co-signed with a BUS US-31 ("Business US-31") route designation, leaving US-33 completely co-signed with other routes, as it had since it was first commissioned in the state. The BUS US-31 designation, however, was soon removed.
Another 25 years would pass before another major change came to US-33, this time a drastic shortening of the highway scaled it back to US-12 on the south side of Niles. This left the highway as a shadow of its former self, running only 2.83 miles in the state. Another decade passed before the remainder of US-31 in Michigan, as well as the portion through South Bend and Mishawaka, Indiana easterly to Elkhart, was decommissioned. The purpose for this major change was to allow the Indiana Department of Transportation to remove the route of US-33 along the Elkhart-South Bend stretch. This could not be done without MDOT going along with the plan and similarly decommissioning their portion of US-33. This was done in 1998 and the last portion of the highway in Michigan was redesignated as an extension of M-51.
|US-33 is commissioned in Michigan, being routed concurrently with US-31 for its entire route from Indiana to its terminus in downtown St Joseph. Interestingly, US-33 in Michigan would not appear by itself in Michigan for more than 25 years. The state highway department couldn't have possibly known of the coming of I-196 and I-94 way back in the 1930s...|
|c.1942–45||At some point during World War II, US-33 is extended northerly 9 blocks through downtown St Joseph. Formerly terminating at the southern jct of US-12 & US-31 (cnr Niles Ave & Main St), US-33 now ends at the cnr of Main St & Ship St, where US-12 & US-31 turn easterly toward downtown Benton Harbor. The reason for this extension is unknown, although it may have had something to do with the State Highway Dept's plans for the new Blossomland Bridge, to be constructed across the St Joseph River at the northern end of Main St immediately following the War.|
|1950||The concurrent US-33 designation with US-12/US-31 in downtown St Joseph is scaled back 9 blocks to end at the jct of US-12/US-31/US-33 (Niles Ave & Main St), as it had prior to the War.|
|1960||US-33 is extended along US-31 northerly from St Joseph for about 10 miles in preparation for the realignment of US-31 along the new freeway under construction from I-94.|
|1962||With the opening of the new I-96/US-31 freeway in Berrien Co northeast of Benton Harbor, the US-31 designation is routed northerly from Scottdale along what had been M-139 to I-94, then northeasterly via I-94 to the new freeway and northerly to the end of the freeway at Hagar Shores Rd (present-day Exit 7). The former US-31/US-33 through St Joseph between Scottdale and Hagar Shores Rd becomes solely US-33. The last half-mile of US-33 is signed concurrently with US-31 along Hagar Shores Rd in a "wrong-way concurrency:" US-31 NORTH and US-33 SOUTH run westerly along Hagar Shores while US-31 SOUTH and US-33 NORTH run easterly.|
|1963||The I-196 (formerly I-96)/US-31 freeway is extended north of Hagar Shores Rd, and the former concurrent US-31/US-33 routing via Hagar Shores becomes solely US-33.|
|US-33 is drastically scaled back from north of Coloma to end at jct US-31 & BUS US-12 in downtown Niles. The former US-31/US-33 between Niles and Scottdale becomes solely US-31 and all of the ex-US-33 between Scottdale and I-196/US-31 at Exit 7 north of Coloma is redesignated as M-63. While the changeover from US-33 is made official on this date, it's unclear precisely when the route markers themselves are changed, although it appears to be around this same time.|
|The portion of BUS US-12 from BUS M-60/Oak St southeasterly via Main St to the US-12 & M-60 interchange southeast of Niles is removed from this routing and transferred onto the 11th St alignment, joining BUS US-31 there and supplanting the US-33 designation in the process. US-33 is scaled back to a terminus at the US-12 interchange south of the city at the new eastern terminus of BUS US-12 as well. It has been reported, however, that this change may have been made in 1987 in terms of signage in the field with the actual jurisdictional transfer taking place in 1994. —Thanks Marc!|
|The Standing Committee on U.S. Route Numbering of the American Association of State Highway & Transportation Officials (AASHTO) officially approves the request by the states of Michigan and Indiana for the "Elimination of U.S. Route 33" on this day at their scheduled meeting in Des Moines, Iowa. The text of the request reads: "Eliminate the U.S. Route 33 designation between the present terminus at the intersection of U.S. Route 12 south of Niles, Michigan, and the intersection with U.S. Route 20 in Elkhart, Indiana."|
|1998 (Apr)||In early April, US-33, the fifth US Highway designation to disappear from Michigan (the others were US-16, US-25, US-102 and US-112), is decommissioned and replaced by an extension of M-51 southerly from downtown Niles to the Indiana state line to meet the newly-designated Indiana SR-933. All US-33 route markers in Michigan were replaced by M-51 signs during the second week in April. The route marker removal takes place almost exacly one year after official approval to do so was granted by AASHTO.|
- Michiana Roads - part of Marc Fannin's Roadfan.com website dedicated to the area of Southwest Michigan and Northern Indiana known by many as "Michiana."
- Niles Area Trunklines Map, 2010– – After decades of regular reroutings, transfers and changes in route designations, the Niles area can be quite confusing when it comes to its highway routings. This map displays the Niles area as it exists at present.
- US-33 - from the Indiana Highway Ends website.
- SR-933 - from the Indiana Highway Ends website.
- End of US highway 33 - from Dale Sanderson's Endpoints of US highways website.
- M-51 Route Listing
- M-63 Route Listing
- M-139 Route Listing