US is far from finishing deveping, fortunately or unfortunately. Take trains, for example, area where US is far behind China, Japan, or European countries, despite the size of its territory. I'm sure there are other examples.
http://4.bp.blogspot.com/_LKZQT6pv_oU/TBqKqQaCcaI/AAAAAAAAA6...
http://www.mckinsey.com/industries/infrastructure/our-insigh...
If the US had a similar political climate the east coast would already have high speed rail from New York to Miami.