Look no further than California. We are still using many roads built in 1970 or earlier, when the population was 19 million people, to transport some 40 million people (probably more than that) in 2019.
Many small towns have refused to upgrade massively-overcrowded local roads on the theory, "If you build it, they will come. So we just won't build it at all." Which is completely wrong, people will still come anyway, and suffer needlessly every day hitting potholes, and wasting minutes of their lives daily on overcrowded narrow roads that were built for traffic conditions that existed 75 years ago. Refusing to upgrade roads is a cowardly cheapskate (and completely ineffective) way of dealing with growth, IMO.