The nation's unemployment rate shot up from 8.1 to 8.5 percent last month, new figures out today show, as employers continued to slash jobs in the face of slumping demand.

The economy shed 663,000 jobs in March, the fourth straight month in which job losses have topped 600,000, according to Labor Department data.

A total of 5.1 million jobs have been lost since the recession began in December 2007, and more than 13 million people are unemployed.

The labor market is actually weaker than the official unemployment rate indicates. Groups excluded from the official count include people who are working part time but would rather be working full time, people who want to work but haven't looked for a job in the past month, and people who have become discouraged and given up looking. If those groups are included, the unemployment rate is 16.2 percent, up slightly from February.