The race to build high-speed rail in the United States is on! Er... sort of. California has plans to build a high speed line from San Francisco to Los Angeles by 2028. Amtrak, for its part, has a grand vision to transform the Northeast Corridor into a high-speed system by 2040. The problem? Both dreams require a lot of cash to see to completion. And it's still not clear that the money's there. Let's take a look at the competitors:

1) California The push to build high-speed passenger rail in California hasn't exactly been a smooth process. But it is, at last, moving forward: Last Friday, the state legislature agreed to plunk down $4.6 billion in voter-approved bond money to begin construction on the initial link between Bakersfield and Fresno. (The federal government will then chip in another $3.2 billion in stimulus.)

But even if California can now get started on the nation's first high-speed rail network, it's not clear that the state can actually complete the task. At the moment, the state has about $13 billion at its disposal. That first operational phase of the system, running between Merced and San Fernando Valley, is expected to cost about $31 billion. A full system that stretches from San Francisco to Los Angeles is projected to cost $68 billion, all told. It's still not entirely clear where the rest of that money will come from.

California voters, after all, don't sound thrilled with approving more bond issues for the project. Congress isn't a likely source of new funds for rail, especially with Republicans still controlling the House. As Yonah Freemark points out, the transportation bill that passed last week contained precisely zero additional funding for high-speed rail. One possibility, floated by California Gov. Jerry Brown (D), is that the state will use revenues from its carbon cap-and-trade program to build the line, although the state's Legislative Analyst Office has raised questions about whether this is even legal.

2) Amtrak's Northeast Corridor. Meanwhile, out East, there's another plan for a grand high-speed rail network in the works. This one, some analysts say, might be more realistic. But it also requires lots of cash.

On Tuesday, Amtrak released its latest vision (pdf) for transforming its popular Northeast Corridor — which currently carries about 12 million travelers annually — and turning it into a true high-speed rail network. Instead of the Acela Express, which only rarely reaches top speeds, Amtrak's new trains would cruise at top speeds of 220 miles per hour. A trip from New York to Washington D.C. would take just 94 minutes, instead of the current three hours. Boston to D.C. would take three hours.

As Alex Goldmark of Transportation Nation explains, Amtrak is actually making a more modest proposal compared to a version released in 2010: "[The new version] scales back the total cost, drops planned stations, and devotes much more attention to realistic, phased implementation," he writes.

The project would roll out gradually, first acquiring new trains, then adding  tracks in areas like New York and New Jersey, as well as building the new Gateway Tunnel across the Hudson River. Unlike California's plan, which starts as a link between two mid-sized cities, the Amtrak vision would continually provide benefits to a heavily trafficked rail route over the years, reducing travel times along the way (graph via Carl Franzen):

Yet the Amtrak plan isn't cheap either — the whole thing would cost some $151 billion over the next 28 years. The company has commissioned a team to try to explore (pdf) other funding options, including fare increases and outside private investors. (Amtrak is also getting some of the high-speed rail stimulus money that Florida Gov. Rick Scott (R) rejected.)

But ultimately, Goldmark notes, the federal government would likely have to kick in more money to make high-speed Amtrak a reality. And even though Congress gave Amtrak a slightly bigger budget in the last transportation bill, at $1.2 billion, it doesn't look like there's a lot more forthcoming at the moment. Which means that the competition between California and the Northeast to build the nation's first high-speed rail work might prove to be one of the slowest races ever seen.