Summary: Pursuant to a congressional request, GAO provided information on commuter rail service in Wisconsin and Illinois, focusing on: (1) current studies conducted on commuter rail service between Milwaukee and Chicago; (2) the availability of funding to extend commuter rail service from Kenosha, Wisconsin, to Milwaukee, Wisconsin; and (3) the potential for using state funds currently provided to finance Amtrak's Hiawatha passenger rail service between Milwaukee and Chicago to finance commuter rail service between Milwaukee and Kenosha. GAO noted that: (1) the Southeastern Wisconsin Regional Planning Commission is currently conducting a feasibility study to evaluate the potential for extending commuter rail service between Kenosha and Milwaukee; (2) the project would be subject to federal transportation planning requirements, with the final selection of projects for implementation being made by the local metropolitan planning organization in consultation with state officials and local transit operators; (3) several sources of federal funds may be available to finance commuter rail service, including federal transit funds and flexible highway funds; and (4) any decision to use Wisconsin funds from Amtrak's Hiawatha service for commuter rail service between Milwaukee and Kenosha would require, at a minimum, action by the Wisconsin legislature.