Vox Teen Beat magazine no. 1, which was issued in California in late March / early April, 1965, contains on page 4 a picture (below) of a Vox promotion at the Disc Jockey Carnival held at the Los Angeles County Fair, Pomona, 25th-31st December 1964 - probably one of the earliest promotions to take place in the States. The magazine as a whole is available here .

Photographs of Vox users ("dealer photos"), banners and posters are arrayed around the open-air stall set up by Bill Harris Music. One can just make out the "VOX" logos on the headstocks of the guitars.

Los Angeles County Fair at Pomona, Disc Jockey Carnival, 25th-31st December, 1964. An AC100 with Foundation Bass cab at left.

A short entry on the Carnival from "The Jan and Dean Record" by Mark Moore, available here.

The "Pasadena Independent", 24th December, 1964.