The US Department of Energy national laboratories have driven scientific computing since the early 1950s. LANL's MANIAC I ran the H-bomb calculations in 1952; NERSC was established with a CDC 7600 in 1974. The ASCI program (1995), launched after the nuclear test moratorium, pushed the field from gigaflops to teraflops to petaflops. Today three US labs operate exascale machines: ORNL's Frontier (2022, first exaflop), ANL's Aurora (2023), and LLNL's El Capitan (2024). NERSC serves DOE's open-science community. Hover any machine for details.