Born in
Brooklyn, Samuelsen became a track worker on the
New York Subway and joined the
Transport Workers Union of America (TWU) in 1993. In 2009, he was elected president of the union's Local 100, in which role he negotiated an agreement covering 38,000 workers. Samuelsen was elected as president of the TWU in 2017, its youngest leader since
Mike Quill. He was also elected as a vice-president of the
AFL-CIO. Samuelsen joined NYC Mayor-elect
Zohran Mamdani's transition committee in November 2025. As head of the TWU, he has supported legislation mandating that MTA subway trains have a two-person crew. Critics described two-person crews as costly and unnecessary, as most of the world’s major train lines have either one-person crews or have moved to full automation. ==References==