INDOT’s Reference Post System

In 1999, the Indiana Department of Transportation decided that it was time to come up with a system that would help better keep track of features along the roads that for which it was responsible. While is would be based, according to INDOT, on the mileage of the road, it was not a milepost system. It was a locator for maintenance items, other than signs, on the state highway system.

RPS 86 on US 40, Marion County, Indiana (Washington Park Cemetery). From Google Maps, snipped 23 December 2020.

There are many parts to the system. The one that most people would have seen, but not really noticed, were the signs that were put up for use with the system. These consisted of small blue signs with a mile number on it, with a smaller sign, if needed, below it with an offset to that mile on it. The signs themselves were barely wider than the post they were on. Very small in relation to most highway signs. Since they are technically only for INDOT use, their size wasn’t a concern. The public wouldn’t notice them, lessening the sign pollution that departments of transportation have been trying to keep under control forever.

RP 88, Offset .88, US 40 bridge of Buck Creek, Cumberland

I really wish I could have had a better snippet for the offset post, but then, the idea was to give the reader the image of what they roughly look like, so the reader would know what to look for.

The RPS manual is very detailed in its information. For instance, the picture to the left is listed as “RP_U_40_Post_86,” meaning “Reference Post, US 40, Post 86.” The one on the right is listed as “CUMBERLAND CORP. LINE BR 4588 O BUCK CREEK,” at least in the 2004 manual.

US 40 is a very prime example of why this system isn’t to be used as a mileage post system. The system was setup prior to the 1 July 1999 decommissioning of US 31, SR 37 and US 40 inside the Interstate 465 loop. What was, in 1999, marked as mile 86 on US 40 is, in 2020, at mile 92.37 on that very same road in 2004. In 2016, the last update from INDOT, it was listed as US 40 mile 65.179. The legal definition of US 40 was lengthened when it was rerouted along the southside of Indianapolis on I-465 in 2004. By a little over six miles. By 2016, the extra mileage along I-465 was removed to show a more accurate road mileage count towards INDOT’s limit of 12,000 miles.

But there is a bit more to the reference post system that comes into play. Each highway listed in the RPS not only includes the complete mileage for the road in Indiana, but they are also listed by the mileage per county, as well. For instance, reference post 86 above is listed as Marion County mile 24.06 in 2004. In the 2016 manual, that mileage is 5.027.

Then, the reference post system records almost everything along the road. This includes EVERY village/town/city street that intersects with the posted road. For instance, near reference post 86 is, in the 2004 manual, “86 + 0.21 24.52 IR 4193 LT (DELBRICK LN).” At reference post location 86.21, 24.52 route miles into Marion County, Delbrick Lane connects to Washington Street (US 40) on the left (north) side of the road. Directions are listed from the increasing number of the reference post. Every street is listed, although almost none of them have a reference post sign.

Also, the corporation limits of towns and cities are listed by the reference post location, although there is no reference post installed most of the time. This even includes old corporation limits. For instance, in the 2016 manual, reference post 85+0.686 is listed as “City or Town Limit – Indianapolis.” Post Road is reference post 86+0.668. Legally, Indianapolis continues for another at least two miles (the sign welcoming one to Indianapolis is west of German Church Road, the county line is another mile east of that, but that is in the town of Cumberland. And even legally, Cumberland is part of Indianapolis. It is as confusing as all get out, but suffice it to say, for the past 50 years, the city limits of Indianapolis have been the county limits of Marion County, with some exceptions. Certainly not Post Road.

But the idea of the legal multiplex of I-465 with almost every INDOT road in Marion County (there are two that don’t mix with I-465: US 136 and SR 135) that brings up another question. What about multiplexes of state roads?

When the system was created in 1999, it was designed with a hierarchy of roads. That hierarchy was interstate, US highway, then state road, in that order. INDOT does not use the term “multiplex” officially. It is called “travel over” in Indiana. The following picture comes from the INDOT RPS guide of 1999 showing how “travel overs” are handled when it comes to marking the mileage of the road.

Indiana Department of Transportation Reference Post System Users Guide, May 1999.

As you can see, near Frankfort, US 421 takes precedence with the little blue signs. SR 39 is junior to SR 38 when it comes to the signs, only due to the fact that 38 is before 39 numerically.

The system underwent some changes between 2004 and 2015. In 2015, it was made perfectly clear that the manual may contain some mistakes, but that every effort was taken to avoid them.

There was also a special note involving US 40 in Vigo County. When US 40 was removed from most of Vigo County, and rerouted along I-70 and SR 46, the RPS system was not changed to reflect that. The section of US 40 that “travels over” SR 46 is still labelled as SR 46. Here is INDOT’s explanation: “US 40 in Vigo County has a special issue that needs to be addressed. Due to relinquishments and creating a travel over for US 40, the alignment does not follow the historic path. US 40 now traverses where SR 46 has traditionally been and SR 46 is considered the Travel Over on US 40. However, the existing reference posts are still for the SR 46 route and are running in a contrary direction to the increasing direction of US 40. Therefore, for the purposes of this book, RP and Offset for the first 3 miles of US are based on the State Log Measure until it reaches the traditional location for US 40 and then jumps to RP 11 + 00 at the intersection of SR 46 and US 40.”

I mentioned above about the original system being put in place prior to the decommissioning of routes in Marion County. It is important to note that there were more routes affected than just those that were moved to I-465. Those routes were US 31, SR 37 and US 40. The mileage on those roads got weird, yes. But there were two others that were affected by the change…and one most people didn’t even realize.

SR 135 was rerouted from Troy Avenue to Thompson Road, cutting two miles out of the official route. This just required moving the little blue signs from north of Thompson Road, and surveying what else would need signs. And what wouldn’t.

The other route affect wasn’t even marked when it was decommissioned. Shadeland Avenue on the east side of Marion County was still legally SR 100 from I-465 to US 40 (Washington Street) until 1 July 1999. For the longest time, the only marker on SR 100 was a smaller blue sign below the reference post signs that read “100.”

INDOT has available on their website the RPS manuals for 2004, 2015 and 2016. Also available is the users guide from 1999. Here are the links for each: Users Guide200420152016

Original SR 31 and the Pike’s Peak Ocean-To-Ocean Highway

Just a short post to show how state roads have changed.

I have covered Auto Trails and the original state road numbers several times over the past nearly two years. I had done a post about the rerouting of the Pike’s Peak Ocean-To-Ocean Highway through Indiana. But the original route, as covered by fellow blogger (and ITH Facebook Group co-admin) Jim Grey, traveled across the western part of the state using the US 36 corridor. (The latest is “US 36 and the Pikes Peak Ocean-to-Ocean Highway in Danville, Indiana,” among others) I’d like to say it followed the current US 36, but it’s been moved several times over the years.

As I had mentioned in other posts along the way, many of the roads that were added originally to the state highway system were part of the Auto Trails systems that crossed the United States. When the Pike’s Peak road was taken into the state system, it was given the designation “State Road 31.” Well, sort of.

OSR 31 started in the west at OSR 10, across the Wabash River west of Montezuma. From there, it went through Montezuma, Rockville, and Bainbridge to Danville. From Danville, the PPOO rumbled across Hendricks and Marion Counties along what is now Rockville Road (and Rockville Avenue – because Rockville Road didn’t connect to Washington Street directly until later). The original SR 31, however, connected to the National Road (then Original State Road 3) at a completely different location.

Strangely, the route of the original SR 31 is now not part of the state highway system. Current SR 39 leaves Danville via Cross Street south towards Martinsville. Original State Road 31 turned south from Main Street on Jefferson Street. Jefferson Street turns into Blake Street, then Cartersburg Road. The state road connected to OSR 3 southeast of Cartersburg.

The drive from Danville to Cartersburg is quite a nice one.

With the Great Renumbering in October 1926, original state road 31 became US 36. Again, sort of. The section from Danville to Cartersburg was removed from the highway system at that time. US 36 continued on into Marion County, as shown in the article “Road Trip 1926: US 36.” Just like the original eastern end of OSR 31, the original eastern end of US 36 is now gone, ending at a parking lot.

I also covered a reroute that was put in place along US 36, after the Great Renumbering, at Bainbridge.

A Quick Look At Today’s State Roads, From A Historical View

A Facebook direct message from a reader of the blog started the research bug going again. Now, while I am still looking up information on his particular subject (transportation to Center Valley in Hendricks County, particularly a possible railroad there), part of his subject did come up. As well as a few others. Today, I want to look at the things that I have found while researching that topic…while not finding much about the topic.

The “town” of Center Valley is along the route that would become State Road 39 just north of the Morgan-Hendricks line. A post office existed there from 1855 to 1902. But what is important is the route that rumbles north to south through the town…the aforementioned SR 39. It wouldn’t be until 1932 when that section of SR 39 was added to the state highway system. But, the designation “state road” goes back quite a bit…like 1833.

The 17th General Assembly of Indiana passed into law several state roads. The first I want to mention would be the one that would make Center Valley (or, more to the point Centre Valley) a place. The route that would eventually become SR 39 was built as the Martinsville-Danville-Frankfort State Road. The southern end would be part of the state highway system from 1920 – the bridge over White River west of Martinsville. The northern end would be part of original State Road 6, connecting Lebanon to Frankfort. As original SR 6, it would become SR 39 with the Great Renumbering.

Two more state roads would from Martinsville would be added to Indiana with this meeting of the General Assembly. The first is one that would not become part of the state highway system. It was described as “an act to locate a state road from Martinsville, in the county of Morgan, by the way of Cox’s mill and Solomon Dunagan’s, in said Morgan county, to Stilesville, in the county of Hendricks.” This is an example of how the General Assembly would set up a “state road” through a particular person’s land. I would assume that what is now Tudor Road, southeast of Stilesville, was part of this road.

Another state road project including Martinsville did make it to the state highway system… eventually. The act created “a state road from Martinsville, in Morgan County, to intersect the state road leading from Madison to Indianapolis, at Edinburgh, in Johnson county by the way of Morgantown in said Morgan county.” This state road would be added back into the state highway system in the 1930’s…as State Road 252. A history of that road is available from ITH here.

But Martinsville wasn’t the only beneficiary of that particular meeting of the General Assembly.

A state road was created by the General Assembly to connect the town of Lagrange, in Tippecanoe County, to Logansport, in Cass County. Where is LaGrange? Well, it was a town along the Wabash River at the Warren-Tippecanoe County line. It was founded by Isaac Shelby in 1827…and had a post office from 1832 to 1835. It’s prime was with the Wabash Canal during the riverboat era. When the Wabash Railroad was built on the opposite side of the Wabash River, the town of LaGrange just dried up and disappeared.

Another road that was created at that time would connect Williamsport to the Illinois-Indiana State line via Lebanon (sic), now West Lebanon, and the now abandoned town of Chesapeake (about two miles east of Marshfield). This route will require some research.

Part of the road that would become, in time, SR 46 between Newbern and Bloomington would be added as a state road in 1833. The original road would start at the Michigan Road in Napoleon, travel through Camden (unknown today), Newbern, and Columbus to Bloomington. The section from Newbern to Columbus was part of the state highway system as SR 46, until INDOT truncated SR 9, turning the old SR 9 into SR 46.

Stilesville would be mentioned again as a state road was created to connect it to Crawfordsville via New Maysville.

The last road for this article would be a road that is still in existence, more or less, but not part of the modern state highway system. The description of the act was “to locate a state road from Green Castle, in Putnam county, to Carlisle, in Sullivan county, by way of Manhattan in Putnam county and Bowlingreen and New Brunswick, in Clay county.” Some day, I want to do more research on this road.

Indianapolis and the Original ISHC State Road System

I have posted much about the creation of the Indiana State Highway Commission. As of the posting of this article, the age of the Commission is either 103 or 101 years old. The original ISHC was established in 1917…but met with a lot of problems. It was finally nailed down in 1919 and made permanent.

This also creates a dating problem when it comes to the state highways. The first five state highways, then known as Main Market Roads, were established in 1917 with the original ISHC. Two of those original Main Market Highways connected to Indianapolis. The original National Road had been given the number Main Market Road 3. The Range Line Road, connecting Indianapolis to Peru, and through further connections, to South Bend, was given the Main Market Road 1 label.

When it was finally established, the ISHC changed the name of the Main Market Road to State Road, in keeping with other states surrounding Indiana. The markers used along the roads, painted onto utility poles like the old Auto Trail markers were, resembled the image to the left…the state shape with the words “STATE ROAD” and the route number. In this case, as of 1920, State Road 2 was the original route of the Lincoln Highway through northern Indiana.

The state highway system was designed to, eventually, connect every county seat and town of over 5,000 population, to each other. Indianapolis, as the state capital and the largest city in the state, would have connections aiming in every direction. Most of those roads marked with the original numbers would still be state roads into the 1970s and early 1980s, before the Indiana Department of Highways started removing state roads inside the Interstate 465 loop…and INDOT finishing the job on 1 July 1999. These road were removed for state statutory limitation reasons, and I have discussed that in a previous blog entry. So I won’t do it here.

The original state road numbers that came to Indiana varied greatly, as did their directions. There were no set rules when it came to state road numbers. They were assigned as they came…and stayed that way until the first renumbering of 1923, or the Great Renumbering of 1926.

Let’s look at the original state roads in Marion County, some of which actually did not reach Indianapolis itself.

State Road 1: As mentioned before, State Road 1 was originally called Main Market Highway 1. North of Indianapolis, it followed the Range Line Road, a local Auto Trail, through Carmel, Westfield, to Kokomo and points north. The route north followed Meridian Street north to Westfield Boulevard, then Westfield Boulevard on out to Carmel and beyond. In Carmel, the old road is still called Range Line Road, and serves as the main north-south drag through the town, as it does in Westfield.

South of Indianapolis, State Road 1, like its Main Market Highway predecessor, followed the old Madison State Road out of the city to Southport, Greenwood, Franklin and Columbus. The original SR 1 route is still able to be driven through the south side of Indianapolis, with the exception of the section replaced in the 1950s by the Madison Avenue Expressway. But Old Madison Avenue exists, if you can find your way back there.

While the entirety of original State Road 1 became US 31 with the Great Renumbering, bypasses in Marion County were put in place very early. The northern section, through Broad Ripple, and Carmel was replaced as early as 1930. The southern section, including the Southport/Greenwood bypass, was put in place in the 1940s.

State Road 3: As mentioned above, Main Market Highway/State Road 3 followed the National Road through Marion County. One exception to this is the section of the 1830s National Road that crossed the White River downtown. That section of the old road was removed in 1904 with the demolition of the National Road covered bridge and its replacement with a new, and short lived, Washington Street bridge. With a couple of exceptions other than that (the Bridgeport straightening of the early 1930s, and the new Eagle Creek bridge built in the late 1930s), the old road was followed very accurately until the mid-1980s with the creation of White River State Park. The successor to original SR 3, US 40, was moved to make room for the park. Both US 40 and US 31 lost their designations on 1 July 1999 with the removal of those two routes inside the I-465 loop.

State Road 6: This old state road was a through route when it came to Marion County. From the north, it followed the route of the original Indianapolis-Lafayette State Road from Lebanon. After passing through downtown Indianapolis, it left the county using the original Michigan Road on its way to Shelbyville and Greensburg. The original State Road 6 followed the Michigan Road Auto Trail, not the Historic Michigan Road, meaning it still went to Madison, but it went by way of Versailles, which the historic road did not. With the Great Renumbering, the northern SR 6 became US 52, while the southern SR 6 became SR 29 – later to be renumbered again to US 421.

State Road 22: This road, as it was originally laid out, only lasted from 1920 to 1923. Out of Indianapolis, it followed the old Mooresville State Road through southwestern Marion County. It was designated the original route from Indianapolis to Martinsville, as described in this blog entry. This road will be discussed again a few paragraphs from now.

State Road 39: Another 1830s state road that was taken into the Indiana State Highway Commission’s custody in 1919. This road followed the old Brookville State Road from the National Road out of the county through New Palestine to Rushville and Brookville. The original end of that road, both the 1830s original and the 1919 state highway, is discussed here. The road would become, in October 1926, the other section of US 52 through Indianapolis. It would also eventually become the first state highway removed inside the I-465 loop in Marion County. And even then, it would be rerouted in the late 1990s to go the other way around the county.

That covers the 1919 highways. More would come to Marion County before 1923.

State Road 12: Originally, this road, north of Martinsville, was the old State Road 22 mentioned above. When a new SR 22 was created, the SR 12 number was continued from Martinsville to Indianapolis along the old Vincennes and Mooresville State Roads. This road, in October 1926, would become part of the new State Road 67.

State Road 15: While the southern route of the Michigan Road was State Road 6, the northern part, heading off to Logansport, was added later and given the number State Road 15. The entire route of the historic Michigan Road would never become a state highway, but major sections did…although late in the creation of the state highway system. With the Great Renumbering, this road became SR 29, and in 1951, redesignated, like its southern half, US 421.

State Road 22: Here we go again. State Road 22 was given to the route between Indianapolis and Paoli. In 1919, that included the route along the west bank of the White River from Martinsville to Indianapolis along the Mooresville Road. This was changed by 1923 to keep SR 22 on the east side of White River, where it followed the old Paoli State Road, and the Bluff Road, through Waverly to the south edge of downtown Indianapolis at Meridian and South Streets. This was one of the routes of the Dixie Highway through Indianapolis, and would later become part of SR 37 in 1926.

State Road 31: In 1920, when this road was originally created, it turned south to connect to the National Road west of Plainfield. It had followed the Rockville Road from Montezuma to Danville, then turned southeasterly to meet State Road 3. By 1923, the road was moved from what would later become part of what is now SR 39 to continuing on the Rockville Road into Marion County. State Road 31 would meet the National Road outside the city limits of Indianapolis at what is now the intersection of Holt Road and Washington Street. It would become US 36 before it was extended along the new section of what is now Rockville Road to the intersection at Eagle Creek with Washington Street.

State Road 37: One of two state road numbers that still served Indianapolis after the road numbers were changed in October 1926 (the other being State Road 31). The original State Road 37 left Marion County in a northeasterly direction on its way to Pendleton, Anderson and Muncie. Inside the city limits, the street name was Massachusetts Avenue. When it reached the city limits, the name of the road changed to Pendleton Pike. This still occurs today, with the name change at the old city limits at 38th Street. In October 1926, the number of this road would change to State Road 67.

There were two other major state roads in Marion County, but they weren’t part of the state highway system until after the Great Renumbering. One was the Crawfordsville State Road, part of the original Dixie Highway, connecting Indianapolis to Crawfordsville via Speedway, Clermont, Brownsburg, and half a dozen other towns. It would be added to the state highway system by 1929 as State Road 34. The number would change later to US 136.

The other road was the original Fort Wayne State Road, also known as the Noblesville State Road, but even more commonly called the Allisonville Road. It would be added to the state highway system in 1932 as State Road 13. Less than a decade later, its number would be changed to the more familiar State Road 37.