Jane Maria Swift (born February 24, 1965) is an American politician and businesswoman who served as the 69th Lieutenant Governor of Massachusetts from 1999 to 2003 and Acting Governor from 2001 to 2003. She is the only woman to perform the duties of governor of Massachusetts, doing so from April 2001 to January 2003. At the time she became acting governor, Swift was 36 years old, making her the youngest female governor or acting governor in U.S. history.