Personal tragedy came for Young in 1917 when he lost his wife Cecilia to cancer. He spent more time in Paris to recover, and once again returned to New York City. It was there, at a dinner in 1921 given by art collector Duncan Phillips, where Young first met J. Alden Weir’s daughter, Dorothy Weir. Her father had died in 1919, but Dorothy herself was an artist and involved in promoting her father’s legacy. More coincidental meetings with the two followed, which then turned into planned meetings in Branchville, Paris and New York City as acknowledged friends. Young and Dorothy married in 1931, and he moved to Branchville in 1932. “No matter how friendly [J. Alden] Weir always was to us of the younger artists, he never introduced us to any of his three charming daughters,” Young recalled. “We never met any of them until after he died. But it was no use. I married the most beautiful, the finest, the most talented of them, Dorothy.”
In 1932, Young commissioned his son-in-law Oliver Lay to build a new sculpture studio on the grounds of the Branchville farm. It was in here that Young would create his largest work. In 1939, he was awarded a long-awaited commission from the Mormon Church and the State of Utah for a monument commemorating Utah’s early history. The monument he created, entitled “This is the Place,” derives its name from the words Brigham Young said on entering Emigration Canyon, near Salt Lake City. Mahonri Young did all the work on the sculptures in his Weir Farm studio with the help of one assistant, Spero Anargyros. Although he considered the monument his crowning achievement, it was not accomplished without frustrations: his relationship with members of the monument commission was cantankerous; World War II made travel and working conditions difficult; and he was afraid his creative powers were waning. In the end, he had to fight to be paid. Nevertheless, at the dedication on July 24, 1947, he made the simple, poignant statement: “Next month, come the ninth of August, I will be 70 years old. This is the greatest day of my life.”