Among the more than 11,000 color slides in this archive documenting commercial architecture in the U.S., 1969-2008, frequent subjects include restaurants, gas stations, movie theaters, motels, signage, miniature golf courses, and beach and mountain vacation resorts. Approximately half of the slides show sites in California, Florida, Michigan, New Jersey, New York, South Carolina, and Texas, but all 48 contiguous states are represented.

Margolies' Roadside America work chronicled a period of American history defined by the automobile and the ease of travel it allowed. Emerging with the prosperity of the post-WWII era, roadside and commercial structures spread with the boom of suburbanization and the expansion of paved roads across the United States. Yet, in many instances, the only remaining record of these buildings is on Margolies' film, because tourist architecture was endangered by the expansion of the interstate system and changing travel desires. Margolies' work was influential in the addition of roadside buildings to the National Register of Historic Places beginning in the late 1970s.

In his photography, Margolies utilized a straightforward, unsentimental approach that emphasized the form of the buildings. These structures were usually isolated in the frame and photographed head-on or at an oblique angle to provide descriptive details. Given the breadth of his subject matter, common typologies and motifs in vernacular architecture can be identified through their repetition. While environmental context is only occasionally provided, Margolies' eye was often drawn to signage or other graphic elements of buildings that expressed the ingenuity or eccentricity of their makers.