Horizons Track Identify

This is definitely from the 1958 "Magic Highway, U.S.A." episode of the Disneyland TV show:

You can hear the same audio in this YouTube copy of that episode:

The Comment tag in the MP3 file is correct:
By looking at various videos of Horizons, I am confident that this is the complete audio that accompanied the 3rd video screen.

Recorded in 2002, encoded with LAME --r3mix

The script for the Horizons ride on INTERCOT.com confirms it:
The third screen is shaped liked a TV set with black lit TV antennas and the "Mars and Beyond" sign behind it. A segment from Magic Highways goes like this:

Male Announcer: On entering the city, the family separates - father to his office, mother and son to the shopping center. These new forms of vehicles will bring about special purpose roadways. Office buildings will combine unique parking and elevator services. ...