There was another thread about this, and the OP mentioned minors - there are no minors required! Then someone else gave the chords, but the formatting went awry so they were all mis-placed. I sang it in C last night, but used G,D, and A - capo 5. Here's my take on it - chords written just before the syllable where change happens:

The verses go:
(G)Across the North Da(C)kota (G)Hills, the twilit road un(D)winds
(G)The setting sun sprays (C)showers of (G)gold, across the (D)dark green (G)pines.
(G)The evening shadows (C)change from (G)grey, to an (C)ever deepening (D)blue,
And I'm (G)somewhere in Am(C)eri(G)ca, a world a(D)way from (G)you.

And the chorus goes:
(G)And the road goes (C) on and(D)and(G)on,
(G)And the road goes (C) on and (D)on........ and(G)on.

If you really can't survive without a minor, you could put in Am for the word "deepening"!!