"Metro did not get started because the freeway got stopped. Metro was already in the plan."
I got that information from "The Great Society Subway: A History of the Washington Metro" by Zachary M. Schrag (Baltimore: Johns Hopkins University Press, 2004): "The 1959 Metropolitan Transportation Study Plan 'awoke the wrath of District residents,' notably 'the revolution of 1960,' led especially by Cleveland Park residents (through whose neighborhood the Northwest Freeway would have been constructed, leading to the proposed Three Sisters Bridge) and abetted by the new Kennedy administration," Schrag wrote. "The city’s response was to fight the highway construction and push for rapid transit instead." Yes, there was much opposition to Metro even after it was being built. But it was not really moving forward until about 1966, though, well after the revolution of 1960. "Washington, DC, was able to pay for much of its share by transferring funds from the unbuilt Interstates within its boundaries." Maybe Schrag was wrong, or maybe I misunderstood what he wrote.