While Cubscouts & Webelos have certain neckerchiefs as a set part of the uniform, US Scouts wear neckerchiefs in various colors. Usually, the troop decides what they want to wear. My oldest son's troop wore navy blue with a silvery-gray overlocked hem & back corner BSA embroidery. At his Eagle ceremony, he recieved one in white trimmed in red, with a 3-color eagle design on the back. The BSA catalog carries several different color neckerchiefs in stock, & custom designs can be ordered, as shown here:



This pic is from http://www.chiefneckerchief.com/

I think it is traditional to wear the neckerchief over the collar, but my son's scoutmaster insisted on them wearing it under the collar.

Sherry