In the 1920s, the Mexican labor movement was gaining steam and, wanting to show their support and international solidarity, the AFL decided to hold their convention in El Paso. Tobin served as a delegate and joined Gompers on a march of more than 900 workers across the International Bridge separating the two nations. U.S. and Mexican workers joined in solidarity, walking in lockstep from El Paso to the Mexican Federation of Labor headquarters in Juarez, right across the bridge. Gompers spoke, pledging loyalty and fraternity.
During the turbulent 1920s, Tobin emphasized several policies to the membership that he believed to be the underpinnings of his leadership.
In October, Tobin married Irene Halloran. Prior to 1922, Tobin lived in a $2.50 a day room at the Indianapolis Grand Hotel. For many years, the room served as his home away from home when he worked at the Teamster headquarters. Marrying Irene would allow Tobin the chance to put down some roots after more than a decade occupying his small room at the Indianapolis Grand Hotel. Life in Indianapolis no longer seemed a waiting game for his return home to Boston. Irene looked after son Joseph and daughter Katharine, the two youngest of the Tobin children, and joined the General President at union functions and political dinners with good friends John Gillespie and his new wife, Ann Hogan Gillespie, a founding member of the Bookkeepers, Stenographers and Office Employees’ organization of New York City.
The year following the death of his first wife was particularly tough for Dan Tobin. Balancing work between the Teamsters and the AFL, all while juggling life between Indianapolis and Boston, left the Teamsters General President and AFL Secretary-Treasurer with little patience for ineffective leadership. Although the IBT continued to run smoothly under thanks to devoted International leaders like Tom Hughes, Mike Casey and John Gillespie, Tobin was growing tired of the infighting between members of the AFL Executive Board. AFL President Samuel Gompers, one of Tobin's close friends and most influential mentors, had always been cautiousness in supporting pro-labor initiatives. Never one to bite his tongue, Tobin became infuriated by the old man's decision to oppose unemployment legislation.
In August of 1920, Tobin’s wife of 30 years, Annie Reagan Tobin, died unexpectedly from complications caused by undiagnosed diabetes. Annie had been at their small summer house in South Massachusetts when Dan received the terrible news at his room in the Indianapolis Grand Hotel. He rushed back to Boston on the first train leaving Indianapolis.
Throughout the war, AFL President Samuel Gompers served by President Woodrow Wilson as representative to the Advisory Committee of the Council of National Defense (1917 to 1919), on which he helped to establish an unprecedented wartime labor policy that clearly laid out government support for independent trade unions and collective bargaining. At the war's end, Wilson appointed AFL President Samuel Gompers to the Commission on International Labor Legislation at the Versailles Peace Conference, where Gompers helped create what would become the International Labor Organization (ILO).
The war brought about unavoidable social changes. New inventions and technologies included both marvels and horrors, and seemed to emphasize and quicken the pace of the world’s move into the “modern age.” Industry was changing across the globe and, in order for the U.S. to stay competitive, Tobin was asked by President Woodrow Wilson to study production efforts. Due largely to his relationship with Wilson and growing stature at the AFL, Tobin became a national figure during this time; as a result, he became more than emboldened more than ever before to advance the union cause in the name of reform.
Tobin, along with 79 international union presidents, met with members of the AFL executive council in March 1917, a month before the United States entered the war, to pledge their support to the war effort (should war happen). The decision to extend support to the Wilson administration was in part a demand that the federal government accept the presence of labor leaders on boards dealing with national defense questions.