Not Quite Halfway There: Dayton, Ohio’s I-675 Bypass

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 (  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, 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.I6757

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:,_Ohio

Here, There, and Everywhere: Washington D.C.’s Many Unbuilt Highways

For the end of 2018, we conclude with a post on the nation’s capital.  With the recent announcement of planning to build new headquarters in Crystal City, Virginia, local citizens and officials have questioned whether the transportation system of  Washington, D.C. can handle the increased load on its system.  The D.C. Metro has been criticized for years — with many residents of the area arguing that the iconic subway/local rail system is not far-reaching and comprehensive enough to meet the needs of many commuters.


The history of the D.C. Metro is also intertwined with the history of the freeway system in the nation’s capital — namely, that some of the Metro lines were built along corridors where Interstate highways might have run.  Critics might argue that Washington D.C. has the worst of both worlds: an inefficient, incomplete rail system combined with an inefficient, incomplete expressway system.  Whether you commute by car or without a car in D.C., you’re likely to run into hassles and headaches.

DC traffic

If you want to live in Washington D.C., you better get used to a busy commute!


What makes Washington so unique from every other city in the United States, besides being the seat of the federal government?  A lot of it has to do with the transportation system.  Much of the planning for the city’s original layout was borne from the mind of one man, a French military engineer by the name of Pierre L’Enfant (1754-1825).  L’Enfant had a logical plan for the layout of the District of Columbia:  streets that ran north-south would have a number (1st, 2nd, 3rd, etc.) while streets that ran east-west would have a letter (A Street, B Street, etc.).  Streets that ran in a diagonal manner would be christened as as avenue with one of the state names (Pennsylvania Avenue, New York Avenue, etc.)  You can read more details of this plan in a fascinating article at here.

All very sound and orderly, but when it came time for Washington, D.C. to come up with its own freeway plan in the mid-1900s, the process was anything but.  Numerous changes and revisions were made, and to this day, much of the D.C. freeway system, especially around the downtown areas, lies in bits and pieces.



Plans from 1955 Yellow Book


Basic Freeway Plan 1958

1958 Plans



1971 Plans


While it isn’t possible to cover all the canceled/altered/abandoned highway projects in one post, here are some of the more notable ones:



Currently I-95 runs along the eastern half of the I-495 beltway, but this was not the original plan.  As we saw with I-40 in Memphis, I-95 was to have made a direct cut through the city.  The original plan (coming up from the south) was for I-95 to cross the beltway, travel the entire length of I-395, and then turn northeast, eventually merging with the College Park/I-495 beltway interchange.  The “Northeast Freeway” had several different proposed routes.  The latest one, from the early 1970s, would have had I-95 as an eight-lane freeway running through the North East sector of the city along the Pepco power line and B&O Railroad corridors.  You can see evidence for the continuation of I-95 inside the beltway by the “over-engineered” interchange at College Park, which takes south-bound drivers to a Park and Ride on the Metro Green Line:




part of the proposed North Central Freeway.  Before 1975, I-270 in Maryland was designated I-70S.  While it currently terminates at the northwest corner of the I-495 beltway in North Bethesda, plans existed to extend the freeway into D.C. itself.  Originally the freeway was to run along the same route as Canal Road and the Clara Barton Parkway before meeting up with I-66.  The proposed route was then changed, with I-70S traveling along the I-495 beltway before turning south near Takoma Park, eventually merging with then-proposed I-95 In the North East part of D.C.  The freeway was to be six lanes and travel parallel with the B&O railroad, with a cleared right-of-way.  Residents of D.C. and Takoma Park stridently and occasionally violently opposed the highway, concerned over proposed demolitions in the Woodside Park and Sligo Creek Park neighborhoods.  The proposed highway was abandoned in the early 1970s.


Also known as the North Leg Freeway.  Up until the 1970s, plans existed to extend I-66 eastward by 1 1/2 miles from its current terminus at U.S. 29 and K Street.  I-66 was to have run via tunnel underneath K Street before emerging at ground level to merge with I-95 (currently designated I-395) near New York Avenue.


Map of the proposed I-66, I-95, and I-295 extensions in the central part of D.C. 

Inner Loop 1280

A slightly modified proposal showing more detail.


Interstate 266 was to have been a short connecting freeway running much of its length along the Potomac River.  The western terminus was supposed to have been where Sprout Run Parkway crosses I-66 in Arlington, Virginia.  From there, I-266 was to run along the current route of Sprout Run, cross over the Potomac along the proposed Three Sisters Bridge, and then turn east, running along Canal Road NW before merging again with I-66 near Rock Creek and Potomac Parkways and K Street.  Strong, and occasionally violent protests against the planned Three Sisters Bridge during the 1960s and 1970s caused the I-266 plan to be abandoned.  The only segment of the proposed freeway to see completion became known as the Whitehurst Freeway (U.S. Route 29), which runs  for approximately 0.8 miles.


I266 three sisters bridge map

Proposed route for the western segment of I-266.


three sisters bridge

An artistic rendering of the proposed Three Sisters Bridge in Arlington.


Also known as the Anacostia Freeway.  Originally intended to follow the route of I-695 and become part of the “Inner Belt” in downtown D.C.  Other proposals had the interstate running along D.C. Route 95.


Interstate 695 is only two miles long, but there were plans to extend the highway further east as well as west.  During the 1960s proposals were made to extend I-695 west, which would have brought it in the vicinity of the Washington Monument and Lincoln Memorial along Maine and Independence Avenues, before terminating at I-66 near the Constitution Avenue interchange:



In the 1990s another proposal was made, this time to extend the freeway east along Southeast Boulevard, eventually merging with D.C. Route 295.  The goal was to relieve congestion on the heavily-traveled John Philip Sousa Bridge.



Southeast Boulevard exiting off to Pennsylvania Avenue.  The highway at left, which runs under the Penn. Avenue overpass to RFK Stadium, was originally intended as an eastern extension of I-695.



Interstate 595 was originally conceived as a spur freeway linking I-395 with Reagan National Airport in Arlington.  It was to have followed the same path as current U.S. Highway 1.  The route was never upgraded to Federal Interstate Highway standards.



Wikimedia map showing some of the various highway proposals for Washington D.C. during the 1950s – 1970s.

With the advent of coming to town, it will be fascinating to watch the city’s debate over transportation continue and what plans will be approved going forward.

Thanks to all you great readers for an exciting journey here in 2018!  Rest assured, there will be much more to post in the new year!


Additional Sources:,_D.C.),_D.C.)