The New York City Transit division says it gives passengers the notes so they can prove they're not lying about being delayed while riding the subway.
Passengers request the delay verification letters over the phone. NYC Transit verifies the date and time of the delay and sends an official note in the mail in one or two weeks. It mails 34,000 notes a year.
Each letter shows the subway line taken and the durations of the trip and the delay.
NYC Transit is working on an online system so it can accept Internet requests and e-mail the excuse letters.