Over the past two decades, U.S. cities have wasted close to $200 billion on high-cost, low-performance rail transit projects. But that will nothing compared to the plans rail nuts have for high-speed intercity rail.

Last November, 52 percent of California voters approved $9 billion in funding for a San Francisco-to-Los Angeles high-speed rail plan. The total cost of the plan is expected to exceed $45 billion, and California expects Uncle Sam to pick up at least half the tab. If it does, Florida, Illinois, Texas, and a few dozen other states will all want federal funding for their own high-speed rail plans.

The House version of the stimulus package included no money for high-speed rail. The senate version included $2 billion. Thanks to Senator Harry Reid (D‑NV), who wants a Las Vegas-to-Los Angeles high-speed rail line, the final version of the bill included $8 billion. (Conservatives have attempted to portray this as an earmark, but Reid says the $8 billion will be distributed through competitive grants.)

Earmark or not, $8 billion won’t even cover the down payment on a high-speed rail network. Based on the projected costs of California’s system and the length of high-speed rail proposals in the rest of the U.S., I estimate that a national high-speed rail network will cost the U.S. well over $500 billion. By comparison, the Interstate Highway System, adjusted for inflation to today’s dollars, cost $450 billion.

What will high-speed rail do? As my Cato policy analysis reveals, studies in California and real-life examples in Europe shows that its main effect will be to put profitable airlines out of business. It will only take about 3 or 4 percent of cars of the roads in rail corridors. Though costing more than interstate highways, a national high-speed rail network will never carry even a fifth as many people as the interstates, and virtually 0 percent of the freight. High-speed rail operations might save a little energy, but the energy cost of construction will more than wipe out any long-term operational savings.

Adding $8 billion to the stimulus bill will do nothing to stimulate the economy, as there are no shovel-ready high-speed rail projects in the country. But it does put us one more step down the path of wasting another half trillion or so dollars on an obsolete form of transportation.