Bloomberg maintains an interesting collection of state-by-state numbers, including infrastructure needs. They only consider a limited number of things: roads, drinking water, and airports. I'd like to have figures that included more factors — ah, how pleasant it would be to have
One of the obvious things that jumps out is that high-population states do better. California, New York, Florida, and Illinois all fall into that group. The most likely reason would seem to be that there are economies of scale involved in the things Bloomberg measures. An airport can serve more people in a high-population state; highway lane-miles are used by more people; doubling the capacity of a water- or sewage-treatment plant doesn't mean that the cost of the plant will be doubled.
Another factor appears to be that states with high population growth over the last 20 years do better. California, Colorado, Texas, Georgia and Florida are examples. In this case, the likely reason would be that rapidly growing populations have made infrastructure spending a critical need. To use Colorado as an anecdotal case, since I live here and pay some attention, Denver built a major new airport, my suburb greatly expanded its water-treatment plant, and I-25 along the Front Range has been subject to an entire series of improvements (if you drive its length, it's not whether part of it is under construction, it's a matter of how much).
I think I'll just sum this up with the obvious statement: "There are new parts of the country, and old parts of the country, and the new parts tend to have more and shinier stuff per person."