The Dark Energy Survey Collaboration collected information on hundreds of millions of galaxies across the universe using the U.S. Department of Energy-fabricated Dark Energy Camera, mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter Telescope at CTIO, a program of NSF NOIRLab. Their completed analysis combines all six years of data for the first time and yields constraints on the universe's expansion history that are twice as tight as past analyses.