Working: Researching, Interviewing, Writing by Robert A. Caro:
The legislative act that unified New York created a city of five boroughs, but only one of them—the Bronx—was on the mainland of the United States, so the new city was really a city of islands. It was Robert Moses, more than any legislature or any other individual, who tied those islands together with bridges, soldering together three boroughs at once with the Triborough Bridge (and then tying two of them, the Bronx and Queens, even more firmly together with the Bronx-Whitestone and Throgs Neck Bridges), spanning the Narrows to Staten Island with the mighty Verrazano, tying the distant Rockaways firmly to the rest of the metropolis with the Marine and Cross-Bray spans, uniting the West Bronx and Manhattan with the Henry Hudson. Since 1917, seven great bridges have been built to link the boroughs together. Robert Moses built every one of those bridges.