After years of planning, building, geopolitical wrangling, and workforce challenges, the world’s largest semiconductor foundry, Taiwan Semiconductor Manufacturing Co. (TSMC) is officially starting mass production at an advanced chip-manufacturing facility in Phoenix in 2025. The fab represents the arrival of advanced chip manufacturing in the United States and a test of whether the 2022 CHIPS and Science Act can help stabilize the semiconductor-industry supply chain for the United States and its allies.