Constructing a retractable dome over the United States is clearly the choice for the 'next big thing'.  The benefits would be both immediate and long term:

Immediate benefits include putting millions of Americans back to work, revitalizing the country's manufacturing base, and solving the border control issue virtually overnight, as soon as the first stages of the dome are complete.

Long term benefits include a longer growing season (every American could afford all the peppers he/she desires, much like gasoline is virtually free in Saudi Arabia- A pepper in every pot), and allow the US to take an even larger role in solving the problem of world hunger.  As the ravages of winter would be avoided, the happiness of every American would be increased, leaving them with more energy to pump into the economy.