Economic opportunity is tied to location, more than ever before, according to a county-by-county report last year from the nonprofit Economic Innovation Group.

• New jobs are clustered in the economy's best-off places, leaving one of every four new jobs for the bottom 60% of zip codes.
• Most of today's distressed communities saw zero net gains in employment and business establishment since 2000. In fact, more than half have seen net losses on both fronts.
• Half of adults living in distressed zip codes are attempting to find gainful employment in the modern economy armed with only a high school education at best.

America's labor force also has become increasingly dependent on large companies, thus narrowing geographic diversity and, arguably, keeping a lid on wage growth.

Go deeper:

• The wildly uneven recovery from the Great Recession
• America's wage crisis no longer looks temporary