Eh it’s not just construction of entirely new highways but highway expansion. Plenty of examples of this.

According to the Bureau of Transport Statistics the US highway system went from 4,050,717 miles in 2009 to 4,171,125 miles in 2019. This is a delta 120,408 miles, or an increase of 2.9%. This is system miles, not even lane miles, so it will not include highway expansion.

Actually correlating this down to individual routes in an exhausting endeavor, given all the places these could be recorded. But I found that we did designate 7 new highways in the past 10 years, including I-14, I-11, I-87, I-41, I-42, I-2, and I-22.

California seems uniquely incapable of building anything, so of course a freeway there has stalled.

Elsewhere the US continues build tons and tons of roads. According to the Bureau of Transport Statistics the US highway system went from 4,050,717 miles in 2009 to 4,171,125 miles in 2019. This is a delta 120,408 miles, or an increase of 2.9%.

The 710 might be an interesting example, but it's not exactly indicative of a trend.

So an enlightened Fordist shipping conglomerate would try to densify urban cores, where it is most efficient to get people their cheap stuff.

No, it's because rail doesn't get the massive subsidies that roads do. Roads are artificially cheap to use, especially for trucking that does the majority of the damage and pay minimal road fees, while rail has to pay for itself. It is very hard for rail, passenger or freight, to compete with the largess of federal tax dollars for road usage. If road fees were matched to the actual cost of road maintenance, like they are with rail, a lot of freight would shift over to barge and train overnight.

Simply put, railways are much more efficient between two fixed points than roads. They require much less fuel per ton, and they require much less labor, land, and capital equipment per person mile or ton mile. If the costs were properly priced in, consumers of various different types would strongly prefer rail for transit between fixed points (e.g. city to city). But currently the inefficiency of road usage is paid for by the federal government.

The density argument is massively overstated. Ohio has roughly the same density as France 282/mi^2 vs. 269/mi^2, and it's not even our most dense state. The fact that states like Ohio don't have anywhere close to the rail network that France has is a consequence of political decisions, not economics or the built environment.