Consumer attitudes about the job market improved dramatically in the first half of March, as consumer confidence jumped to a 16-year high.

Consumers who saw jobs as "plentiful" rose to 31.7 percent from 26.9 percent in February, and those who said they are "hard to get" fell slightly to 19.5 percent from 19.9 percent, according to the Conference Board.

But one key number economists look at is the differential between jobs being plentiful and jobs seen as hard to get. That rose to 12.2 from 7 last month, the highest since August 2001. During the financial crisis and for the years after, it was negative, only turning positive last year.

JPMorgan economists tracked the number against the unemployment rate, and its improvement shows a sharp correlation to improvements in the unemployment rate. Unemployment, at 4.7 percent, is already super low.