Hall was born Arvo Gustav Halberg in Virginia, Minnesota, one of the towns on the Iron Range. Hall's parents had been founding members of the Communist Party.
At 15, Hall left school and went to work in the north woods lumber camps. There, he spent lots of time studying Marxism. At 17, he joined the Communist Party and became an organizer for the Young Communist League.
In 1934, Hall went to Ohio's Mahoning Valley. Following the call for organizing in the steel industry, Hall was among a handful hired at a steel mill in Youngstown, Ohio. Fearful of being blacklisted if he used his full name, he decided to shorten it by shaving off "Arvo" and "berg," leaving "Gus Hall." The name stuck.
Hall was a founding organizer of the Steel Workers Organizing Committee (SWOC) and a leader of the 1937 "Little Steel" strike. Victory in that strike, huge in everything but name, gave birth to the United Steelworkers of America (USWA) in 1943. Philip Murray, USWA founding president, once commented that Hall's leadership of the strike in Warren and Youngstown was a "model" of effective grassroots organizing.
It was in Youngstown that Hall met Elizabeth Turner. They were married in 1935. Elizabeth Hall was a leader in her own right, among the first women steelworkers and a secretary of SWOC.
Hall and other rank-and-file steelworkers signed up workers who wanted to join a union.
"This had to be a secret operation," Hall wrote in a 1972 letter to the USWA. "Any man who signed was immediately fired if it became known. As a matter of fact, I was fired. It was not until we had collected thousands of such signed cards that [CIO head John L.] Lewis agreed to set up the [SWOC]. I was on the committee that presented the cards to John L. Lewis in the dugout of a baseball stadium where he was the speaker at a Miners' Day rally" in Johnstown, Pennsylvania.
Thus, Lewis was convinced and one of his first decisions was to hire Hall as a full-time SWOC organizer in the Mahoning Valley where he served as an international representative throughout the organizing drive and later as chairman of the strike committee during the strike. Under Hall's leadership, 10,000 workers were recruited to the steel union in the Mahoning Valley.
Later, he resigned his union post to become an organizer for the Communist Party in Youngstown. Hall volunteered for the U.S. Navy when World War II broke out, serving as a machinist in Guam. He was honorably discharged March 6, 1946.
On July 22, 1948, Hall and 11 other Communist Party leaders, were indicted under the Smith Act on false charges of "conspiracy to teach and advocate the overthrow of the U.S. government by force and violence." Many Communists and progressives were jailed, blacklisted, and hounded by the FBI during the McCarthyist Red Scare that followed World War II. Hall spent eight years in Leavenworth Federal Penitentiary for the crime of "thinking" about teaching. The U.S. Supreme Court finally struck down the Smith Act as unconstitutional.
After his release, Hall continued his activism. He led the struggle to reclaim the legality of the Communist Party and addressed tens of thousands in Oregon, Washington and California during those "Free speech" fights.
He became a very popular speaker on campuses and talk shows. He became the leading advocate for socialism USA. Hall argued that socialism in the United States would be built on the traditions of U.S.-style democracy rooted in the United States Bill of Rights. He would often say Americans didn't accept the constitution without a Bill of Rights and they won't accept socialism without a Bill of Rights. He had a deep confidence in the democratic traditions of the American people.
In 1959, Hall was elected CPUSA general secretary. But the McCarthy, Cold War era had taken a heavy toll on the Communist Party. Hall, along with other Party leaders who stuck through the persecution, had to rebuild it.
Throughout the 1960s and 1970s Hall worked to build the Communist Party among the young "baby boomer" generation of activists involved in the peace, civil rights and the new rank-and-file trade union movements.
He ran for president four times, in 1972, 1976, 1980, and 1984, the last two times with Angela Davis. Due to the great expense of running, the difficulty in meeting the stenuous and different election-law provisions in each state, and the difficulty in getting media coverage, it was decided that the CPUSA would suspend running national campaigns, while continuing to run candidates at the local level.
After the dissolution of the Soviet Union in 1991, the party faced a crisis. Hall worked to preserve the party as many members left. He served as leader until his death. By that time, the party had benefited from a steady comeback.