The last time intercity passenger trains served Madison, Wisconsin's capital city, students at the University of Wisconsin campus there were protesting the Vietnam War. The trains stopped running when Amtrak took over passenger service around the country in 1971. But last month, the federal government announced it would give the state $810 million in stimulus money to return passenger trains to Wisconsin's second-biggest city for the first time in more than four decades.The $8 billion in federal stimulus money billed as "high-speed rail" funding that will pay for the Wisconsin improvements is going to 31 states to improve service on trains of all speeds. But as even the straightforward case of Wisconsin shows, the path for states to actually build high-speed rail promises to be long, costly and, in some cases, politically contentious.