Empty and sun-drenched, this chrome-era postcard surveys the wide main avenue of San Luis Río Colorado, a small Sonoran border city that sits just across from San Luis, Arizona — Tecate beer signage dominates the right-hand storefronts, a scattered handful of late-1950s and early-1960s American cars idle at the curbs, and the flat desert horizon stretches endlessly ahead under a cloudless cobalt sky, evoking the quiet, unhurried pace of a Mexican border town that never quite achieved Tijuana's tourist frenzy but offered its own authentic charm to those who crossed.