Having left the Rockies behind, we now start to enter the Midwest heartlands and the breadbasket of eastern Colorado. In this segment and part of the next we will ride with or closely parallel Interstate 76, US 6's inheritor in most of this region. I-76 is one of the split Interstates, a historical curiosity from its origin as eastern and western routings of the former spur Interstate 80S, with an eastern section running from I-71 in Akron, OH through Pennsylvania to I-295 in Bellmawr, NJ. (Despite US 6's extensive routing in Penna., we'll only intersect its auxiliary I-476; we will not see I-76 again once we leave Sterling.) The 188-mile western section here is almost entirely within Colorado, running from Arvada at I-70 to the state line and continuing for a brief two miles to the only Nebraska exit, its terminus with I-80 near Big Springs, NE. The other major split Interstates are Interstate 86 (with its segments in Pennsylvania/New York and Idaho), Interstate 88 (with its segments in Illinois and New York) and Interstate 84. We saw I-84 first as I-80N in US Highway 395 Part 22; we'll see it again on the East Coast with this highway much later. That eastern segment of I-84 is particularly noteworthy as it replaced the old alignment of I-86, which moved north to New York. More about that when we get there.

I-76 (as I-80S) had been planned in Colorado as early as 1958, at first from I-25 in Denver to I-80; the western extension to I-70 took nearly two decades and was not completed until 2002. In 1976, AASHTO established its "no suffixes" policy which eventually left Interstate 69 and Interstate 35 as the only Interstates with suffixes (I-69C, I-69W, I-69E, I-35W and I-35E) today and I-80S was renumbered to I-76 in 1976. Although it is popularly believed this western number reflects the Bicentennial, in actuality it hails from 1876, the year Colorado was admitted as a state.

US 6 is corouted exclusively with I-76 except for an unsigned loop in Wiggins until it reaches the outskirts of Brush, from which it becomes the I-76 business route but retains US 6 shields, and appears in the CDOT route log as a segment of Route 006. There are many well-preserved old alignments through the small towns in this region, but lamentably there was just not enough time to capture them on our way through, and none of them are signed.

In this section we meet US 34. US 34 between its western terminus in Greeley, CO and where we meet it in Wiggins, CO actually was US 6, at least from 1931 to 1936. US 6, in those days, continued along US 34 to that point where it terminated at US 85; it had already been extended by 1931 along US 32 (which later became part of US 34) from at least Chicago to Iowa, and US 38 through Omaha to Greeley. An original 1926 highway, US 34 gradually moved west to its present terminus in Granby at US 40 by 1939 as US 6 moved south to what was formerly signed CO 81 and was the original route of the historic Omaha-Lincoln-Denver and Detroit-Lincoln-Denver Highways (more to say about this in Nebraska). US 6 has several meetings with it; Dale Sanderson has a number of alternate views of these junctions. In 1970, the east end was moved out of downtown Chicago to Berwyn, IL where the modern highway terminates for a length of 1,122 miles.

Our intersection with US 34 in Fort Morgan is also the beginning of our co-routing with the famous Overland Trail, which we will discuss in Part 16. Although US 34's crossing through Rocky Mountain National Park at 12,183' is higher than US 6 over Loveland Pass, making it the highest paved through highway in the United States, Loveland Pass is regularly cleared of snow and US 34 isn't which makes the distinction rather academic in the teeth of winter.