Beginning in the 1980s, Vergara applied the technique of rephotography to a series of American cities, photographing the same buildings and neighborhoods from the exact vantage point at regular intervals over many years to capture changes over time.

[4] He began at that time to work systematically, using techniques adapted from sociological methodologies; traveling from one subway stop to the next, he would emerge onto the street and then photograph the surrounding blocks, fanning steadily outward.

[6] The rephotographic method, with its rigorous demands for systematic return, exact replication of vantage point, angle of view, and lens choice, had emerged originally out of the need for scientific evidence of change over time in ecological niches.

After the publication of his second major work, American Ruins, Vergara's reputation was fully established; he won a MacArthur Foundation "genius grant" in 2002 and served as a fellow at the Mid-Atlantic Regional Center for the Humanities (MARCH) at Rutgers University in 2003–2004.

[9] Slate and Time magazines have also commissioned him to produce "mines" of his work—collections that feature topics or themes, from GM automobiles[10] to distant traces of the World Trade Towers.

Trees, vines, and wildflowers would grow on roofs and out of windows; goats and wild animals—squirrels, possum, bats, owls, ravens, snakes and insects—would live in the empty behemoths, adding their calls, hoots and screeches to the smell of rotten leaves and animal droppings.

[13] The proposal launched a public conversation about representations of the city's built environment[14] and is considered an important statement in the debates surrounding deindustrialization and ruins photography.