Please answer a question about the following article about Federal Aviation Administration:

On the eve of America's entry into World War II, CAA began to extend its ATC responsibilities to takeoff and landing operations at airports. This expanded role eventually became permanent after the war. The application of radar to ATC helped controllers in their drive to keep abreast of the postwar boom in commercial air transportation. In 1946, meanwhile, Congress gave CAA the added task of administering the federal-aid airport program, the first peacetime program of financial assistance aimed exclusively at promoting development of the nation's civil airports.

What helped ATC controllers in their drive ot keep ahead of the postwar boom in commercial air transportation?
radar