American Airlines, United, and Delta are set to dominate U.S. aviation in 2025 with major fleet modernization efforts. Each carrier is investing heavily in new, fuel-efficient aircraft and retrofitting older planes to cut costs and emissions while improving passenger comfort. Supported by a $22 billion FAA infrastructure program, these upgrades are expected to boost sustainability, efficiency, and competitiveness, positioning the three airlines at the forefront of the U.S. aviation industry.