One of the many interesting things about this segment of US 34 is that it essentially follows the valley of the Colorado River between its headwaters in Rocky Mountain National Park and its confluence with the Fraser River in Granby. Consequently US 34 also provides access to all of the major water collection components of the Colorado-Big Thompson Project. Those include Grand Lake (Colorado's largest and deepest natural lake) and three artificial impoundments (Shadow Mountain Lake, Lake Granby, and Willow Creek Reservoir). Since there are many examples of highways which were originally built parallel to rivers, but which later had to be realigned because of water storage projects that were built in those valleys, I set out to explore whether US 34 had any historic alignments that existed prior to the reservoirs in the Middle Park area.
The original road heading west from Estes Park up into the National Park was not Trail Ridge Road (current US 34); it was Fall River Road (which is still open to westbound drivers). But Fall River was too steep, too narrow, and too curvy to be of much use as a tourist road. So construction on Trail Ridge began in 1929, and the project was considered complete in 1938.* In fact, that may have been what prompted CDoT officials to request an extension of the US 34 designation into Colorado.
Notice that Grand Lake was the only body of water shown on that map. Also note the town of Stillwater again, as well as highway 280 heading southeast from there alongside a tributary of the Colorado River, but no label for Monarch (more later). The backside of that map featured verbiage and photos highlighting things to do and sights to see along five of the east-west US routes in Colorado. US 34 was included among them, even though it was a brand new route in the state. Likely the rationale for that was because US 34 provides access to one of the most scenic areas in Colorado, and also the most-visited:
...however, by that time it was known that Stillwater was doomed to be submerged beneath the eventual pool of Lake Granby, and 1941 was also the year that construction on Granby Dam began.* Since it is typically necessary for road relocations to be included among the earliest phases of dam construction projects, the removal of Stillwater's label and the new curve on US 34 were likely related to the fact that construction had begun.
Based on that timeline, US 34 existed in Colorado for about two years before construction began on the Colorado-Big Thompson Project. So if any realignments were necessary due to the dams, then US 34 would have followed the older alignment(s) for at least two years, maybe a little longer (depending when the new alignments were open to traffic). But the preceding maps were not detailed enough to determine whether any realignments were necessary.
Highways were not the only things that changed as a result of the water storage projects in the upper Colorado River valley. Even the names of some streams were changed... or at least that is when some of the name changes were recognized.
First, a little background: the portion of today's Colorado River within the state of Colorado was not always so named. From about 1870 until 1921, that stream was known to white settlers as the Grand River.* Grand Lake (the body of water) was named as such by white explorers because it was considered the source of the Grand River. The North Fork of the Grand River flowed into the main Grand where the south end of Shadow Mountain Lake is now. There was also a South Fork of the Grand River, which flowed into the main Grand near where Deer Island is now (in Lake Granby). There was even a Roaring Fork of the Grand; some of that was illustrated on this 1915 map:
There you can see two streams flowed into Monarch Lake from the east: the South Fork and Arapaho Creek. Flowing out of Monarch Lake to the west was the South Fork. At the town of Monarch, the Roaring Fork joined the South Fork.
In 1921 the Grand River in its entirety (from its headwaters in Colorado to its confluence with the Green River in Utah) was renamed as the Colorado River.* So at that time one would think that the North Fork, South Fork, and Roaring Fork all became forks of the Colorado (rather than forks of the Grand). However, based on what I find in the GNIS database, it was a bit more complicated than that. The North Fork Grand did indeed become the North Fork Colorado, but apparently there was some discrepancy about the correct name of the South Fork: some maps referred to it as the East Fork. Rather than trying to decide between those two, the decision was made to change the name of the stream that flows out of Monarch Lake to Arapaho Creek (same as one of the streams that flows in). So what was done with the portion of the South Fork that flows into Monarch? That was renamed to Buchanan Creek. And that leaves one more question: what was the Roaring Fork then considered to be a fork of? Remarkably, it officially became Roaring Fork of Arapaho Creek.
So those are the decisions that were made on paper in 1921. But those changes took awhile to catch on with the general populace. In particular, some maps into the 1940s continued to refer to Arapaho Creek by its old name, South Fork. I believe it was the construction of Lake Granby and its attendant changes (new recreation area, new campgrounds, new roads and trails, etc.) that finally pushed the new toponyms more to the forefront of public consciousness. For instance, the arm of Lake Granby that extends way off to the east was named "Arapahoe Bay" (as opposed to "South Fork Bay"). By the 1950s, most maps had been updated to show Buchanan Creek flowing into Monarch Lake, and Arapaho Creek flowing out:
I find it even more remarkable that the toponym "Roaring Fork of Arapaho Creek" wasn't changed after Lake Granby was formed, considering the fact that it no longer even flows into Arapaho Creek (it flows directly into Arapaho Bay of Lake Granby).
Why spend all of this time on names of streams, anyway? Personally, it was eye-opening when I learned that the Colorado River used to have a South Fork, and when I consider the facts that a.) it is almost completely submerged, and b.) the old name is fading from collective memory, those are both things that I view with a sense of loss.
To wrap it up by getting back to highways: another topic that interests me about this segment of US 34 is its signposted direction. US 34 is ultimately an east-west route, and it is signed east-west in Colorado. But (as I mentioned at the beginning) the "westernmost" 27 miles of US 34 are actually oriented strongly north-south. I realize there are many examples of this type of thing, particularly in places like Colorado that have challenging topography. And I understand that generally it is preferable to sign routes with their ultimate cardinal directions, including any segments that may run counter to those directions. However, exceptions can be made in states that contain the highway's terminus, and exceptions are made in other states.
*Sources and further reading: