I used my GPS last time and noticed 90 mph through portions of western IL, north central MO, and KS. The overnight through KS is pretty quick, and the train rocks and rolls.
There are several long stretches of 65-75 mph; the average speed for the entire trip was 60 mph.
The CO and northern NM portions are sometimes mind-numbingly slow. We were going approx. 9 mph through the Raton and Glorieta area, sometimes hitting a whopping 19 mph.
Keep in mind our trip is always CHI to ABQ. Past ABQ, I'm not sure where the 90 mph stretches are.