A couple of other things, I believe that the Kansas Central was also built to NG and it was intended somehow to connect St. Louis and Colorado, but it never really got off of the ground.
In Texas, in addition to the Texas and St. Louis, the Houston, East and West Texas (today's former SP "rabbit" line was built NG, as was the Kansas and Gulf Short Line, built from Tyler, through Rusk to Lufkin to connect with the HE&WT. Because the K&GSL was narrow gauge, the initial Texas State Railroad was NG also. One of the other unique NG RR's in TX was the Texas Western Narrow Gauge RR which went west from a connection with the HE&WT in Houston, and in fits and starts finally made it all the way to Sealy. From Sealy, it was intended to turn south to go to Corpus Christi and also continue on west to San Antonio and Fredericksburg but never did go either place. What makes it unique is that much of its line, after abandonment became Westheimer Road, which is one of the busiest streets in Houston.