I'm too busy right now to search through their online archives, but Yates' articles typically talk about the "vanishing highways", which is to say the slightly lower number of linear miles of interstate highways in the USA over the last 20 or 30 years. Last time I hit the road, the highways have been just fine. It's the freeways and surface streets that have the most problems.

That doesn't really calculate in to just looking at miles of highway laid out in the great open spaces of the country. As long as there's not a wreck, 4 lane divided highways have always seemed to work pretty well out west. In developed areas, obviously you need higher capacity. Also the last time I read one of his articles on the topic, it was hung up on sheer linear miles of highway, not lane-miles. A lot of the old interstates were only 2-lane roads, whereas now 4 lane divided and even 6 lane in built up areas is far more common. I'd bet we have a lot more lane-miles of highway now than 30 years ago.