You can't put a 100mph high speed train on a freight line, and those freight lines don't cross with other transit arteries nor enter the urban cores where people are. What you say is true, but other than the fact that they are both "trains", it's not the same infrastructure we're discussing.

Speaking as someone who lives near a rail hub (and indeed, one of the busiest transshipment rail hubs in the world) freight rails absolutely do cross other transit arteries, and enter urban cores where the people are. Indeed, in the U.S., most passenger lines actually run on freight lines (including almost all of the Amtrack network excluding a few lines in the Northeast).

100mph is not a "high-speed" train. It's just a train. Freight engines are capable of going up to 80pm with cars, and over 100mph without (but don't for safety and operational reasons). Freight lines are designed for cost efficiency, not speeds, but generally unless your 100mph train is using specialized wheels, it will run just fine on a freight line, though it will need to slow down for turns due to the shortened turn radius on most freight lines.

How exactly do you propose running high speed transit and freight on the same tracks when one is moving 70+mph faster than the other? You know trains are on rails, right?

> The U.S. has the world’s best designed and maintained rail infrastructure

I don’t think you can really compare the infrastructure freight trains use with high speed rail. Designing and maintaining a rail network where trains go at up to 350kph is a much tougher job.

So, I’d argue the US rail infrastructure isn’t even close to being one of the best.

What kinds of things do you feel make it superior in design to eg central europe?

The U.S. rail system is different from Europe's rail: we chose freight over passengers, so it's difficult to make direct comparisons if (as other HN commenters are) your rubric for superiority is train speed.

But in a nutshell: (a) the US rail system is cheaper. The entire freight rail system costs less than what France pays for its significantly smaller system each year, (b) more throughput. Millions of tons of goods travel by rail every day. It's cheaper, faster, and more ecologically friendly to ship by rail than by air, water, or truck, (c) America's rail system is designed to withstand weather features that would obliterate most of Europe's rail lines, like tornadoes and hurricanes.