That's more people than Chicago itself.
If you take Chicagoland as an endpoint and not the city boundaries, Des Moines is also within 300 miles.
Transcontinental high speed rail is, I agree strongly with your subtextual argument, a pipe dream. But regional HSR in the midwest would make a lot of sense.
But I can totally understand stopping your brain at Ann Arbor if the alternative is to go on to Detroit...
One reason existing tracks and routes don't run that frequently is that there aren't the passengers to make them worthwhile. Another is that those tracks are also used for freight.
Otherwise land values rise too high and fast to establish rights of way.
The British and US rail systems were developed as industrialisation progressed, notably IR2 (coal, steam, iron) and IR3 (steel, electricity, precision).
The US rail system was further developed in the wake of depopulation, genocide, and land appropriation from the indigenous tribal peoples. Governmental land grants to railroads were a major funding mechanism.
Development of HSR has tended to be a Post-WWII phenomenon, originating in Japan, then France, Germany, elsewhere in Europe (though generally not the UK), and recently, China.
The usual factor cited has been density, which matters. But both national economic policy and rights-of-way acquisition costs are massive factors, which the more free-market, strong-private propert rights regimes of the US and UK resist.
Wikipedia's list of HSR systems excludes Switzerland, though lines are presently under construction there (notably GBT): including Belgium, China, Denmark, Finland, France, Germany, Greece, Israel, Italy, Japan, Morocco, The Netherlands, Norway, Poland, Russia, Saudi Arabia, South Korea, Spain, Sweden, Taiwan, the United Kingdom, the United States, Uzbekistan, and Turkey.
My lord, what?! Three of the top 25 largest cities in the entire US are within 300 miles of Chicago (Columbus, Indianapolis, Detroit), and the Twin Cities (3rd largest metropolitan area in the US, larger than Chicago itself) are only 350 miles away.
Chicago-Naperville-Elgin, IL-IN-WI MSA 9,498,716
Minneapolis-St. Paul-Bloomington, MN-WI MSA 3,629,190
https://en.wikipedia.org/wiki/List_of_metropolitan_statistic...
But regardless, you can get an idea from the EU. EU rail subsidies amount to 73 billion euro annually. EU rail carried 465 billion passenger-kilometers in 2017, or 300 billion passenger miles. That's a subsidy of $0.24 euro per passenger mile, even worse than Amtrak.
Roads are just really cheap to build and maintain. A 6-lane interstate highway costs $11 million per mile in urban-ish areas: http://blog.midwestind.com/cost-of-building-road. It's going to cost $1.4 billion to add four lanes to the 35 miles of the BW Parkway (which goes through a dense urban area connecting two major cities). At $40 million per mile, that's 1/6 of what it cost to build the Metro Silver line through less dense areas in an existing freeway median. That's 1/9 the per-mile cost of the purple line, a light rail line that mostly travels at grade without its own right of way.
That's because, even with all its faults, averaged over all travelers it beats the heck out of all the other alternatives for trips that would take more than a few hours by car or train. Scalzi's experience, as messed up as it was, is an outlier.
Also, our train system has more than funding parity with roads. Road spending is about $175 billion per year, about half of which isn’t recovered from use fees, for 5 trillion passenger miles. That’s about $0.02 per mile subsidy. Amtrak’s capital expenditures is about $900 million per year, which comes directly from Congress. (Ticket revenue only goes to operating costs.) that’s about $0.13 per passenger mile.
For a guy driving 300 miles, that cost the government $6.00 in road construction and maintenance. For the guy to train that same distance costs the government $39.