Chicago is where all the Class I (i.e., big railroads) meet: UP, BNSF, CN, CP, KCS, CSX, NS. There are several railroad yards in the city and surrounding environments, so much so that the rail lines are really visible on Google Maps who otherwise loves to deemphasize rail routes.

Indeed, Chicago and the Mississippi River is the dividing line in the North American rail network. UP and BNSF dominate western US, CSX and NS the eastern US, CN and CP dominate Canada, and large regionals like KCS, the Mexico side is similarly or more abysmal.

Unfortunately they don’t integrate that well together to form a cohesive network. CP is attempting to buy KCS/KCSM to create something of a NAFTA/USMCA railroad, but it’s not clear it would deliver those benefits without harming competition in the existing setup. Ideally the rail infrastructure would be publicly owned and invested in, and any train operator could transport from any location to any location on the North American rail network.

Yes. But there's one railroad line that goes through North Platte. There once were ~38 railroad lines into Chicago. Some are no longer in service (at least as through lines), but Chicago is still far more widely served than North Platte.

The Chicago region has dozens of very large rail yards, with construction of new yards and expansion of existing yards ongoing. It would take a lot of investment elsewhere to eclipse: Russia/Moscow is making a strategic investment that will pay large dividends for them for decades to come.