US and foreign airlines each carry about half of US international traffic in the latest year. Foreign airlines led clearly in the late nineties and again just before the pandemic, and US airlines led by more during it.
What this shows: The chart covers 1990 to 2024. It plots US carriers and Foreign carriers on a vertical axis of Share of passengers (%). Latest values: US carriers 49.9; Foreign carriers 50.1. Data run through 2024.