It coincided with the rise of the Sears Roebuck catalog:
While it is certainly true that the music was forged in part by the legacy of slavery and the insults of Jim Crow, the iconic image of the lone bluesman traveling the road with a guitar strapped to his back is also a story about innovators seizing on expanded opportunities brought about by the commercial and technological advances of the early 1900s. There was no Delta blues before there were cheap, readily available steel-string guitars. And those guitars, which transformed American culture, were brought to the boondocks by Sears, Roebuck & Co. ... Guitars first appeared in the catalog in 1894 for $4.50 (around $112 in today’s money). By 1908 Sears was offering a guitar, outfitted for steel strings, for $1.89 ($45 today), making it the cheapest harmony-generating instrument available.