The evolution of New York has been illustrated in photographs in countless ways. Two of the biggest collections belong to the city. Between 1938 and 1943, 700,000 stark black-and-white pictures, known as tax photos, were taken to make property assessments and as a jobs program for the federal Works Progress Administration. In the 1980s, a second set of 800,000 photos was taken, also for tax purposes. In both sets, the property's block and lot number is listed on the photos. The photos are available for sale by the city . Fred R. Conrad, a New York Times photographer, returned to 12 of the sites this year. — SAM ROBERTS