When Green's health declined in 1951, Meany gradually took over day-to-day operations of the AFL. He became president of the American Federation of Labor in 1952 upon Green's death, which occurred just 12 days after the death of Congress of Industrial Organizations president Philip Murray. Walter Reuther of the United Auto Workers became president of the CIO. Upon taking leadership of the AFL, Meany put forward a proposal to merge with the CIO. Meany took control of the AFL upon being elected president, but it took a bit longer for Reuther to solidify his control of the CIO. Reuther then became a willing partner in the merger negotiations. It took Meany three years to negotiate the merger, and he had to overcome significant opposition. John L. Lewis of the United Mine Workers called the merger a "rope of sand," and his union refused to join the AFL-CIO. Jimmy Hoffa, second in command of the Teamster's Union, protested, "What's in it for us? Nothing!" However, the Teamsters went along with the merger initially. Mike Quill, president of the Transport Workers Union of America also fought the merger, saying that it amounted to a capitulation to the "racism, racketeering and raiding" of the AFL. Meany's efforts came to fruition in December 1955 with a joint convention in New York City that merged the two federations, creating the AFL-CIO, with Meany elected as president. Called Meany's "greatest achievement" by Time magazine, the new federation had 15 million members. Only two million US workers were members of unions remaining outside the AFL-CIO.

Answer this question "What was the AFL?" by extracting the answer from the text above.
American Federation of Labor