Need help figuring out the history of US 24 over Tennessee Pass in Colorado

[Route66Fan]

I've been trying to figure out the history of the routing of US 24, and it's predecessor "The Pike's Peak Ocean to Ocean Highway" (PP-OO), over Tennessee Pass near Leadville CO, but for some reason, I'm not able to really figure out if the current US 24 follows the old autotrail route, or if it's been changed over the years since 1919. I know that the railroad has been changed & that there was a new tunnel put in through the area in 1945.
This is how this part of the route was described in the 1919 Official Automobile Blue Book (South to North):

Here is the same route being described in the opposite direction (North to South):

Due to not being able to find any county plat maps of the area from the 1910's to 1930's, I can't seem to figure this out. Please help, thank you.

[Max Rockatansky]

I did something for Leadville last year, might be of help:

https://www.gribblenation.org/2020/05/2016-summer-mountain-trip-part-28-us.html?m=1

[Route66Fan]

I did something for Leadville last year, might be of help:

https://www.gribblenation.org/2020/05/2016-summer-mountain-trip-part-28-us.html?m=1

Thanks for the link. I've actually gone back over the section from Pando to Tennessee Pass & I now think that the old alignment in that area follows Resolution Creek Rd (CR 702), Eagle River Rd (CR 714), Jones Gulch Rd (CR 726). The section of old alignment that curves off of CR 714 to CR 726 is even referred to as "Old Hwy".

[NE2]

I think what confuses things south of the tunnel is that the original route closely followed the current route at Keeldar, rather than old US 24 to the east. This makes the railroad crossing at 43.7 fit. https://catalog.archives.gov/id/5829268 confirms that there was a road there.

The 1945 railroad tunnel was just west of the old 1890 tunnel, and shouldn't have affected anything. The crossing at 49.6 was probably a minor branch, unless there was a relatively minor realignment just north of the tunnel with the road somehow cutting across the mainline.

I assume you know about the old alignment between Mitchell and Pando.

[Route66Fan]

I think what confuses things south of the tunnel is that the original route closely followed the current route at Keeldar, rather than old US 24 to the east. This makes the railroad crossing at 43.7 fit. https://catalog.archives.gov/id/5829268 confirms that there was a road there.

I was thinking that it went through Keeler, but I wasn't so sure.

The 1945 railroad tunnel was just west of the old 1890 tunnel, and shouldn't have affected anything. The crossing at 49.6 was probably a minor branch, unless there was a relatively minor realignment just north of the tunnel with the road somehow cutting across the mainline.

I think that the crossing at 49.6 might have led to the old 1890 tunnel. I do notice what appears to now be a spur, on the South end of Tennessee Pass, that branches off the main line & heads East before curving North & ending at where the old tunnel is located.

I assume you know about the old alignment between Mitchell and Pando.

I know where Pando is, but not exactly where Mitchel is\was.

[NE2]

I think that the crossing at 49.6 might have led to the old 1890 tunnel. I do notice what appears to now be a spur, on the South end of Tennessee Pass, that branches off the main line & heads East before curving North & ending at where the old tunnel is located.

The 1890 tunnel was literally just east of the current one. The 1890-1945 route didn't cross any roads that the current route doesn't.
The pre-1890 route can be seen here in blue on the map at the end: http://www.drgw.net/info/TennesseePass I don't think the PPOO used it, as it seems to be significantly longer than the mileage given.

I assume you know about the old alignment between Mitchell and Pando.

I know where Pando is, but not exactly where Mitchel is\was.

https://catalog.archives.gov/id/5829219 (page 12)

Apparently this old alignment curving way to the east *is* the original D&RGW: http://tennpass.blogspot.com/2017/