Unfortunately, I'm not sure who the credits for this song belong to. I'd assume Ernest Martin. I downloaded it years ago from the internet. Unfortunately, I haven't been able to re-find where I downloaded it from. These are the lyrics as I've transcribed them. Note that though Martin has an album released in 1962 with this song as the title song, I believe this is from his 1955 recording with the Norvell Brothers -- it's a little less bluegrassy than the songs I've been able to scrounge up from that album while searching.

Ernest Martin: Heaven's Highway 66

While traveling so many great highways
We're bothered with traffic so thick
Up there's one road that's not crowded
It's the Heaven's Highway 66

CHORUS
I'm traveling the highway to heaven
I've left the old broad way of sin
When the last words are spoken
And the Pearly Gates open
I'll lay down my cross and go in

Each highway on earth has a number
As the prophets have spoken before
That 66 books of the Bible
Is the number to Heaven's bright shore

CHORUS

There's a mansion that's built up in Heaven
John saw it descending one day
Prepared and adorned for the people
That have traveled this Heaven's highway

CHORUS

God's word is the map to that city
The road is prepared and all fixed
Do not turn left as you travel
This Heaven's Highway 66

CHORUS