 Complete the following phrase:  In 1927, McCormack sold his interest in U.S. Trucking and entered the sand and gravel business by obtaining an interest in United Sand and Gravel, a company owned by former Assistant District Attorney Edward J. Chapman and McCormacks cousin and close friend Bronx politician Robert L. Moran. United Sand and Gravel became Transit-Mix, which, as one of only two concrete plants located within the city, provided millions of cubic feet of concrete for public and private construction projects including the Empire State Building, Chrystler Building, United Nations, Radio City, Waldorf-Astoria, New York Central Building, Guggenheim Museum, Lincoln Center, 