Jerry, I remember that song too:

Plod along, plod along the Santa Fe Trail.
Plod along, plod along the Santa Fe Trail.

Oh, the desert sun is bold.
And the desert nights are cold.

On we plod through choking sand,
Cactus, sage on either hand,
Through the bare and burning land.
Oh, the desert stretches wide,
And the Indians watch us ride!

Such a cheerful little song for second graders. I remember the tune too--I have sung this to friends to demonstrate the delights of my Catholic School childhood.