I-75 was developed from several expressways that were planned and under construction before the Interstate Highway system was created in 1956. Detroit was one of the most industrialized regions of the United States at the time, so the demand for highways was earlier here than in many other parts of the country. The southernmost portion has been developed as the Toledo – Detroit Expressway, the southern approach from Detroit as the Fisher Freeway and the northern approach as the Chrysler Freeway. In northern Michigan, the Mackinac Bridge was built as a connection to the Upper Peninsula. These became part of I-75 from 1956. The highway was opened to traffic in many phases between 1956 and 1973.
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Toledo – Detroit Expressway
In the late 1940s, plans emerged for the Toledo – Detroit Expressway, a highway connecting the industrial centers of Toledo, Ohio and Detroit, Michigan. Construction on this highway began in 1952 and the first 25 miles were opened on December 21, 1956 between Erie and Rockwood, already opening up a substantial portion of the rural stretch between Toledo and Detroit. An alternative name for this road was the Seaway Freeway, named after the St. Lawrence Seaway that opened in 1959. In 1957, the border with Ohio was also completedcompleted, but it was not opened until 1959 when the Toledo North Expressway in Ohio was also completed, which happened on May 22, 1959. This completed the highway from Toledo to the southern suburbs of Detroit. On October 12, 1959, the first signposts with the number I-75 were installed, this was the first signposted Interstate Highway in Michigan. The next section opened on December 16, 1963 when the connection continued to US 24 (Telegraph Road) on the south side of the Detroit metropolitan area. This allowed traffic to reach the more developed Telegraph Road. The highway further into Detroit had not yet been built at the time.
The Toledo – Detroit Expressway was later widened to 2×3 lanes. It is not known when exactly this was done, at least before 1993. The connecting section in Ohio was widened to 2×3 lanes in the 1990s.
| from | nasty | length | date |
| Exit 2 Erie | Exit 27 Rockwood | 40 km | 21-12-1956 |
| Exit 27 Rockwood | Exit 34B Sibley Road | 11 km | 00-1x-1958 |
| Ohio state line | Exit 2 Erie | 3 km | 22-05-1959 |
| Exit 34B Sibley Road | Exit 35 Telegraph Road | 2 km | 16-12-1963 |
Fisher Freeway in Detroit
The Fisher Freeway has been built through the south of Detroit, as an extension of the older Toledo – Detroit Expressway. The first part of this was opened on December 28, 1966 between the branch to US 24 (Telegraph Road) and the Schaefer Highway in River Rouge. This was the complete southern half of the Fisher Freeway. In 1967, an extension to Clark Street, including the tall River Rouge Bridge, opened in a highly industrial area. In 1968, the stretch opened along the north side of Downtown Detroit, and on September 16, 1970, the missing section opened southwest of downtown. This completed I-75 throughout the city.
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In the period 2008-2012, I-75 was completely closed for 4.5 years for the construction of a junction with the Ambassador Bridge to Canada. This project was called the Gateway Project and was supposed to improve traffic flow between the United States and Canada. As part of the project, the border complex has been expanded significantly to avoid the queue of waiting vehicles on I-75. A number of residential streets here have been demolished insofar as there were still houses and have become part of the border complex.
In 2017-2018, I-75 south was closed for two years for the concrete replacement and renovation of the River Rouge Bridge, Michigan’s largest bridge. For both the Gateway Bridge and the River Rouge Bridge, I-96 and I-275 are good diversion routes. Due to the vacancy rate in Detroit, the highways in the city are used less intensively than comparable highways in other American cities.
| from | nasty | length | date |
| Exit 35 Telegraph Road | Exit 43 Schaefer Highway | 13 km | 28-12-1966 |
| Exit 43 Schaefer Highway | Exit 47A Clark Street | 6 km | 12-12-1967 |
| Exit 49 Rosa Parks Boulevard | Exit 51 I-375 / Gratiot Avenue | 3 km | 00-00-1968 |
| Exit 47A Clark Street | Exit 49 Rosa Parks Boulevard | 3 km | 16-09-1970 |
Chrysler Freeway in Detroit
The Chrysler Freeway in Detroit.
The Chrysler Freeway was originally planned as the Hastings-Oakland Expressway. In 1957, a motion was passed to name the planned highway the Walter P Chrysler Expressway. Construction on the highway officially began on January 30, 1959. The first two-mile stretch between I-375 in Downtown Detroit and the interchange with I-94 opened to traffic on June 26, 1964. On January 10, 1969, a larger portion of I-75 opened between I-94 and the city limit at 8 Mile Road. This completed the Chrysler Freeway in the city of Detroit. Then on December 6, 1971, the last section in the northern suburbs of Detroit opened, including the large stack interchange with I-696, which would not be put into service until years later because I-696 was still unfinished for a longer period of time.
Between 2016 and 2023, 17 miles of I-75 between 8 Mile Road and State Route 59 in Pontiac was widened to 2×4 lanes. The extra capacity is HOV lanes that are accessible to all traffic outside rush hours. Work started in August 2016 and has been carried out in phases, generally from north to south. The freeway has been completely redesigned and widened from 2×3 to 2×4 lanes. The project cost $1.3 billion. It was originally planned to realize the widening with conventional financing, which would take the widening and modernization until about 2030. In September 2017, it was announced to renovate and widen I-75 as a PPPcontract, the first PPP project in Michigan, which meant that the widening could be partially completed in 2020, 10 years ahead of schedule. A large part was completed in 2020, except for the southern part, which was completed by the end of 2023.
| from | nasty | length | date |
| Exit 51 I-375 | Exit 53 I-94 | 3 km | 26-06-1964 |
| Exit 53 I-94 | Exit 59 8 Mile Road | 10 km | 10-01-1969 |
| Exit 59 8 Mile Road | Exit 62 11 Mile Road | 5 km | 06-12-1971 |
Detroit – Flint – Saginaw – Bay City
The stretch through the town of Flint was originally developed as US 23The first section was the Fenton-Clio Expressway, a north-south route that included part US 23 and part later I-75, which opened from Fenton to Birch Run on June 30, 1958. This stretch was 55 kilometers long, 34 kilometers of which fell under I-75 and included the complete passage through the town of Flint. Further north, construction was underway around Saginaw and Bay City, which opened in late December 1960, including the Zilwaukee Bridge over the Saginaw River. This was the first section of I-75 in Michigan to be signposted as I-75 immediately upon opening. On November 17, 1961, I-75 opened along Saginaw. The southern section between Birch Run and Bridgeport was newly constructed, the actual bypass of Saginaw was the upgrade of the old US 23 bypass of the city. On December 14, 1962, a 55-mile section between Waterford and US 23 opened south of Flint. On December 31, 1963, the last section of I-75 opened between Pontiac and Waterford, completing the highway north of Detroit to Saginaw.
At Saginaw, the Zilwaukee Bridge spans the Saginaw River. This was originally a bascule bridge. This bridge opened to shipping much more often than expected, causing huge traffic jams in the 1960s at bridge openings, with regular hours of waiting. In 1968 there was a traffic jam of almost 100 kilometers during a busy travel weekend. Interstate 675 opened in 1971by Saginaw, who offered an alternate route, because it had a fixed bridge. However, this led to the undesirable situation that there was much more traffic on I-675 than the highway was designed for. That is why it was already decided in the mid-1970s to replace the bascule bridge with a high fixed bridge, the concrete Zilwaukee Bridge. Construction of the bridge began at the end of 1979 but was greatly delayed by accidents during construction. The bridge was opened to the south on December 23, 1987 and to the north on September 19, 1988. The project cost $127 million at the time. The new Zilwaukee Bridge was not only taller, but also doubled the capacity of 2×4 lanes.
I-75 has been widened after initial construction. Between 1973-1975, I-75 was widened to 2×3 lanes between Flint and Saginaw, and from Saginaw to Bay City. The Saginaw section was commissioned with 2×4 lanes in 1987-1988 with the replacement of the Zilwaukee Bridge. The stretch from I-475 in Flint to I-675 in Saginaw was later widened to 2×4 lanes, starting around Flint in the early 2000s, then north to Birch Run around 2005 and later to Bridgeport around 2010. In 2017, it followed to the south side from Saginaw and in 2021 to I-675 at Saginaw.
The section from Pontiac to Flint has also been widened to 2×3 lanes, presumably also in the 1970s. A small piece between the southern interchange with I-475 and US 23 at Flint has remained 2×2.
| from | nasty | length | date |
| Exit 115 US 23 | Exit 136 Birch Run | 34 km | 30-06-1958 |
| Exit 151 Saginaw | Exit 164 Kawkawlin | 21 km | 00-12-1960 |
| Exit 136 Birch Run | Exit 151 Saginaw | 24 km | 17-11-1961 |
| Exit 81 Waterford | Exit 115 US 23 | 55 km | 14-12-1962 |
| Exit 62 11 Mile Road | Exit 81 Waterford | 31 km | 31-12-1963 |
Bay City – Mackinac Strait
I-75 at Saginaw.
In 1957, the Mackinac Bridge opened to traffic. Construction of the highway through northern Michigan’s southern peninsula followed fairly quickly. On October 1, 1959, the first 2 kilometers of this opened along Mackinaw City, originally signposted as US 27. However, the next opening was a lot bigger, when a 39-kilometer section between Indian River and Mackinaw City was immediately opened on November 11, 1960. Construction then proceeded quickly, on November 15, 1962, the section between Vanderbilt and Indian River was opened, making it possible to drive through an approximately 100-mile stretch in northern Michigan.
It then took several years before a section opened again, on November 1, 1967, nearly 40 kilometers of I-75 between Kawkawlin at Bay City to just before Standish, this section runs parallel to Saginaw Bay. The last sections of I-75 between Standish and Grayling were completed during the 1970-1973 period. On November 1, 1973, the final 17 miles between West Branch and Roscommon opened, completing the entire I-75 in Michigan.
| from | nasty | length | date |
| Exit 337 Mackinaw City | Exit 338 Mackinaw City | 2 km | 01-10-1959 |
| Exit 313 Indian River | Exit 337 Mackinaw City | 39 km | 11-11-1960 |
| Exit 249 US 27 | Exit 254 Grayling (South) | 16 km | 09-10-1961 |
| Exit 254 Grayling (South) | Exit 270 Waters | 26 km | 01-12-1961 |
| Exit 270 Waters | Exit 282 Gaylord | 19 km | 16-07-1962 |
| Exit 282 Gaylord | Exit 290 Vanderbilt | 14 km | 31-08-1962 |
| Exit 290 Vanderbilt | Exit 313 Indian River | 37 km | 15-11-1962 |
| Exit 164 Kawkawlin | Exit 188 Standish | 39 km | 01-11-1967 |
| Exit 188 Standish | Exit 202 Alger | 23 km | 02-07-1968 |
| Exit 202 Alger | Exit 210 Cook Road | 13 km | 15-10-1970 |
| Exit 244 Roscommon | Exit 249 US 27 | 8 km | 18-11-1970 |
| Exit 239 Roscommon | Exit 244 Roscommon | 8 km | 00-00-1971 |
| Exit 210 Cook Road | Exit 222 West Branch | 19 km | 00-00-1972 |
| Exit 222 West Branch | Exit 239 Roscommon | 27 km | 01-11-1973 |
Upper Peninsula
Plans for a bridge across the Mackinac Strait between the Lower and Upper Peninsula began as early as the 1880s, when the first colossal bridges were built, such as the Brooklyn Bridge.in New York and the Forth Bridge in Scotland. A formal ferry service was introduced in 1923, which became congested within a few years due to the amount of traffic. In the 1930s, plans for a bridge connection were further elaborated, as a possible project of the Progress Works Administration to combat the economic depression. Between 1936 and 1940, various studies were carried out into soil conditions, currents and wind. But construction did not start as a PWA project and was delayed afterwards due to the outbreak of World War II. A cost estimate of $86 million was made in 1951, but construction was again delayed due to shortages of materials during the Korean War.
Construction of the Mackinac Bridge officially began on May 7, 1954. The bridge was opened to traffic on November 1, 1957. The open section ran for 10 kilometers from Mackinaw City to US 2 in St. Ignace. In 1960 the bypass of St. Ignace opened to traffic. At that time, a 60-kilometer stretch of I-75 was already accessible on both sides of the Mackinac Bridge.
In 1954, the International Bridge Authority was formed to build a bridge between Michigan and Ontario at Sault Ste. Marie to put on. It spans the lock complex between Lake Huron and Lake Superior, and the border between the United States and Canada. However, construction did not begin until the late 1950s and the Sault Ste. Marie International Bridge was opened on October 31, 1962.
Construction of the remaining section on the Upper Peninsula proceeded quickly, and on November 1, 1963, both missing sections between St. Ignace and Sault Ste. Mary opened. This completed the northernmost 250 miles of I-75 in Michigan.
| from | nasty | length | date |
| Exit 338 Mackinaw City | Exit 344 St Ignace | 10 km | 01-11-1597 |
| Exit 334 St. Ignace | Exit 348 St. Ignace | 6 km | 12-11-1960 |
| Exit 392 Sault Ste. Marie | Canada border | 9 km | 31-10-1962 |
| Exit 378 Kinross | Exit 386 Munsing | 13 km | 05-12-1962 |
| Exit 348 St. Ignace | Exit 378 Kinross | 48 km | 01-11-1963 |
| Exit 386 Munsing | Exit 392 Sault Ste. Marie | 10 km | 01-11-1963 |
Traffic intensities
The section between the Ohio and Detroit border is fairly busy, with 60,000 to 70,000 vehicles per day. Within the Detroit metropolitan area, the intensity rises to around 100,000 vehicles, but remains fairly stable. Near the center this even drops to 90,000 vehicles. Only north of downtown does this rise to 156,000 vehicles per day, where I-75 forms the long commuter route from the north. Just north of Detroit itself is the busiest point with 176,000 vehicles per day in 2×4 lanes. To the north this drops quickly, past Pontiac 51,000 vehicles drive. This rises a bit along Flint, but it only gets really quiet from Bay City. The intensities then drop to 9,000 vehicles per day, and in the north of the peninsula even to 7,300 vehicles. Driving over the Mackinac Bridge 11. 000 vehicles, before descending again to about 3,000 halfway through Sault Ste. Mary. About 6,000 vehicles cross the border into Canada every day.
