U.S. airlines lost or mishandled almost 3 million pieces of luggage in 2019, and nearly a third of those were on American Airlines flights.

Fort Worth-based American fell to last in 2019 in the U.S. Department of Transportation’s rankings for mishandled and lost luggage, botching delivery on 8.48 of every 1,000 pieces of baggage. To compare, Southwest Airlines’ mishandled baggage rate was about half that.

The data includes numbers for American and its branded codeshare partners, which captures its own mainline and Envoy regional flights and those operated by its regional affiliates, including Mesa and SkyWest airlines.

Ultra-low-cost carrier Allegiant was the best at delivering luggage and Frontier, another low-cost carrier, ranked second. Dallas-based Southwest was the third-best for handling baggage after ranking second-to-last in 2018 among carriers excluding regional airlines.

American blamed its bad year for baggage on the airline’s troubles, including clashes with union mechanics and the grounding of Boeing’s 737 Max.

“Last year, we faced significant operational challenges that impacted our results, including the grounding of the Max, and, most significantly, a higher number of aircraft out of service,” said a statement from American spokesman Ross Feinstein. “A big contributor to our high [aircraft out of service] numbers was the illegal [union mechanics] slowdown, which disrupted our operation during the peak period.”

American Airlines lost and found led the industry in lost and mishandled luggage in 2019

American Airlines led the industry in lost and mishandled luggage in 2019

U.S. commercial airlines lost about 5.85 bags per 1,000 they handled in 2019. Here’s how the carriers rank: