Mobile data demand is exploding, with aggregate data downloaded quadrupling in the last seven years. New and innovative uses enabled by 5G, as well as the prospect of 6G applications, point towards further increases in expected demand for mobile network capacity. Unfortunately, the U.S. spectrum landscape appears to be stalled, with no clear prospects for significant spectrum reallocations this year and insufficient bands under consideration for reallocation in the coming years. This lack of a spectrum pipeline, coupled with the lapse of the Federal Communications Commission (FCC) auction authority, has raised the prospect of significant capacity constraints in the terrestrial wireless space, and concern that this may limit the U.S.’s ability to be a leader in this area. This paper investigates this capacity constraint and estimates the likely spectrum deficit the U.S. will face over the next decade absent policymakers allocating additional fullpower, licensed spectrum.