Why did unemployment drop so sharply in South Florida during the recession? In part, the cause was a sharp drop in the businesses available to hire people.

That trend has officially reversed itself in recent months, with business establishments on the way back up in both Broward and Miami-Dade.

Broward was late to the rebound, with the establishment count turning positive only recently. Miami-Dade’s establishments have been growing since early 2010, though the gains were fairly weak until the summer of 2011.

Establishment numbers don’t tell the whole story of a rebound, since even one person cleaning houses will be counted as an establishment. As a result, times of high unemployment can give a boost to establishment counts as people are forced to start their own businesses.

But the trends in Broward and Miami-Dade clearly tracked the recession, with the yearly declines beginning in 2008.

Neither county has fully recovered from the downturn, Broward’s latest establishment count from the Bureau of Labor Statistics was about 62,000 in the third quarter of 2011, off 6 percent from its past peak. Miami-Dade’s count of 87,000 is down 1 percent from the peak set just before the 2007-09 recession began.