If every jobless worker in the U.S. could be matched with every available job, the unemployment rate would fall to near zero. That will never happen in reality, but the jobs are there.
On Friday, the Labor Department reported that there were 6.1 million open jobs in the U.S. at the end of February—0.9 for every unemployed worker. That compares with 0.75 per unemployed worker a year earlier, and 0.15 when the recession ended in 2009. And, in a sign that companies are struggling to fill positions, the share of hires per job...