Since 1998, carsharing programs (or short-term auto rentals) in the U.S. have experienced exponential membership growth. As of July 2003, 15 carsharing organizations collectively claimed 25,727 members and 784 vehicles. Given this growing demand, decision makers and transit operators are increasingly interested in understanding the potential for carsharing services to increase transit use, reduce auto ownership, and lower vehicle miles traveled. However, to date, there is only limited evidence of potential program effects in the U.S. and Europe. This paper presents the travel effects of...