Resuming from a long break, we continue down I-75, arriving in Dayton, Ohio, which is best-known for the Wright Brothers, who would pioneer a whole new mode of transportation for the 20th and 21st century. Dayton proved to be no slouch either when it came to ground transportation, either. According to Wikipedia, Dayton’s downtown road system is unlike most other Midwestern cities its size: the streets are very broad, with two to three lanes running in each direction, with ample space for pedestrians and cyclists.
View of South Main Street in downtown Dayton.
Dayton’s freeway system is also unlike its neighboring cities of Columbus, Cincinnati, and Indianapolis. From a strictly logical standpoint, Dayton’s freeway network might have made more sense if it had been built like this:
Instead of looking like what it ended up with:
As you can see from the above map, Interstate 70, one of the longest east-west highways in the United States, misses the city of Dayton entirely, traversing its northern suburbs instead. This might not have been unintentional, since I-70 in Ohio was built to replace traffic along U.S. Highway 40.
What’s really odd about Dayton is that up until the mid-1990s, there were hardly any freeways in the western part of the metro area. Eastern Dayton, in contrast, had several expressways crossing its terrain, including U.S. Highway 35, Ohio State Route 4, and Ohio State Route 844 (a spur freeway that connects to Wright-Patterson Air Force Base), and I-675. I-675 appears as a somewhat malformed semi-circle, connecting I-75 south of Dayton with I-70 near Springfield.
It might be helpful at this point to explain the rationale of three-digit interstates in the United States and why they are numbered the way they are. As a general rule, three-digit interstate highways that begin with an odd number (like 1, 3, 5, and 7) are known as “spur” interstates — they connect the two-digit “parent” interstate with a city’s downtown or central business district (such as I-175, I-375, I-575, etc.) In contrast, three-digit interstates that begin with an even number (2, 4, 6, and 8) are usually “by-pass” or “loop” interstates — going around a city, usually to avoid potentially heavier traffic within the central business area (like I-275, I-475, etc,) and re-connecting with the “parent” two-digit interstate at both ends. Wikipedia has a helpful visual:
Not all three-digit interstates follow these rules, however, and I-675 in Dayton is one of them. Of course, there’s a story behind all of this. So what happened? First, let’s again go back to the planning stages that took place in the 1950s and 1960s. For this particular article, I have to give enormous credit to the author at Daytonology.com (http://daytonology.blogspot.com). Although his website has not been updated in a very long time, and at one point he even voiced his intention to take the site down, supportive fans and readers pleaded with him to leave it as it was, and because of that decision we still have access to a treasure trove of information about the Dayton area. Major credit is also due to user “Jeff” at the forums of urbanohio.com, who also has a wealth of old city maps in his posts.
Before World War 2, Dayton, along with many other cities in the United States, was pre-occupied with how to alleviate heavy traffic and congestion in its downtown area. Talk of creating a network of parkways was proposed as far back as the 1920s, but by the end of the war the discussion had shifted to building a network of higher-speed, limited-access freeways instead. As we’ve seen before in places like Winnipeg, extensive research was conducted to study the traffic patterns of the city, and where the construction of such highways would provide the most benefit.
As you can see from the above map, traffic was particularly heavy along U.S. Highway 25 and Ohio State Route 4. What gets interesting here is the debate Dayton had over where else freeways should be built. By the late 1950s the city had decided on a “hub and spoke” network, with multiple freeways radiating from the downtown area:
Not long after the above plan had been proposed, however, that calls were made for Dayton to have a proper by-pass expressway around the downtown, and by 1962 plans were in place for Interstate 675, which would have connected to I-75 in Miami Township at its southern terminus, and then re-connecting with I-75 in Northridge at its northern terminus:
What then followed over the coming years proved to be a series of messy politics, as the author of Daytonology points out in his series of articles. The original route for I-675 overlapped most of its length with the proposed Southeast Freeway. While the Ohio Department of Transportation signed off on its approval for the plan, the Bureau of Public Roads (a precursor to the Federal Highway Administration) would not, citing the proposed I-675 as a “parallel expressway” — as a result, Dayton was unable to secure federal funding for the project.
By 1965, the proposal for I-675 had evolved to its present day course, swinging to the eastern suburbs around Wright-Patterson Air Force Base and the newly-built Wright State University Campus. Real-estate speculators, it was believed, would also benefit from the altered route. But again, the federal government would only pay for 50 percent of the funding for the new highway — it was up to the state of Ohio and local governments to come up with the rest of the money. As a result, Dayton re-allocated funding that would have gone to freeway development on the western side of the metro area, and used it to complete I-675. Although I-675 was originally slated for completion in 1975, further delays and controversies resulted in the highway not being finished until 1989. The conflict reached a crescendo during 1979, when the Ohio Department of Transportation threatened to sue then-Transportation Secretary Neil Goldschmidt. Goldschmidt had agreed only to fund construction of I-675 only between I-70 and U.S. Route 35. The state government accused Goldschmidt of “a usurpation of the authority of local and state governments to determine the destiny of their highway system.” However, Thomas Downs, who was then a planner for the Federal Highway Administration, cautioned the city of Dayton and the state of Ohio against taking legal action against the Transportation Secretary, arguing that the courts had sided with the federal government numerous times over similar incidents.
“All politics is local,” as the saying goes. Maybe not, but Dayton’s long road with Interstate 675 is a prime example of how federal, state, and local politics collided with each other to make the United States highway system what it is today.
View of I-675 near Wright-Patterson AFB and Wright State University.
Additional Sources:
https://en.wikipedia.org/wiki/Dayton,_Ohio
https://www.kurumi.com/roads/3di/3di-primer.html
http://daytonology.blogspot.com/2008/09/long-road-to-road-i-675-prehistory-to.html
http://www.interstate-guide.com/i-675-oh/
https://www.daytonohio.gov/DocumentCenter/View/290
https://forum.urbanohio.com/topic/1941-dayton-expressway-prehistory/
https://newspaperarchive.com/xenia-daily-gazette-dec-11-1979-p-1/
America's Canceled Highways 
