Arcology:
http://en.wikipedia.org/wiki/Arcology
Arcologies are an avenue of research for dealing with future population density, housing, and environmental issues which it would be wise for the Federal Government, the only one with the funds to really do large scale research and development plans for such, to begin investing in.
By creating planned, efficient, high-density population centers, that are largely self-sufficient, the government can effectively prepare for a growing worldwide population and demand on resources and energy, reducing future costs, and possibly recovering some costs as the arcologies eventually pay for themselves via the rent and utilities costs of the residents and businesses within.