The international neutrino community is developing a long-baseline neutrino program based in the United States with a high-intensity neutrino source and suite of near detectors at Fermilab, and a large liquid argon time-projection chamber (TPC) in the Sanford Underground Research Facility. This exciting program will determine the neutrino mass ordering, search for leptonic CP violation, and over-constrain the leptonic mixing matrix. The large underground detector enables a great deal more physics such as searches for beyond-the-standard-model nucleon decay and measurements of supernova neutrinos. In order to maximize its potential, several challenges must be overcome. I will discuss the program, the challenges, and how the Cryogenic Apparatus for Precision Tests of Argon Interactions with Neutrinos (CAPTAIN) project addresses the challenges.