The East Bay unexpectedly shed 4,000 jobs in December, a month that traditionally sees an increase in employment opportunities.
The job loss was in contrast to the region's unemployment rate, which showed slight declines in both Alameda and Contra Costa counties.
The jobless rate measures employment among people who live in these communities. It counts people who are willing and available for work. Those who have given up searching are not included.
The number of jobs represents what's available in businesses in the region. Some employees come in from outside the area.
In December, the total number of jobs in the East Bay dropped from 959,000 the month before to 955,000.
Officials at the state Employment Development Department said over the past 21 years December has seen on average an increase of 3,400 jobs. Last month, therefore, was 7,400 jobs fewer than normal.
Leisure and hospitality took the biggest hit. That industry lost 2,000 jobs in a month it usually gains 400. Food and drink establishments showed the biggest declines.
Professional and business services shed 1,300 jobs in a month it usually gains 1,100.
Government services had 1,100 fewer jobs, close to the average for December. Manufacturing lost 100 jobs.
Construction was one of the few bright spots. After losing 800 jobs in November, the industry added 400 in December.
Education and health fields saw an increase of 400 jobs while financial services and trade and utilities both saw bumps of 100 jobs.
Cindy Sugrue, a labor market consultant for the state EDD, said it's uncertain why December lost so many jobs. She said the shaky economy is the most likely cause.
"I think it shows there still some struggles out there," she said.
The East Bay's unemployment rate did drop from 9.5 percent in November to 9.3 percent in December. The rate was 10.8 percent in December 2010.
Both Alameda and Contra Contra counties had rates of 9.3 percent. In November, Contra Costa had a 9.5 percent jobless rate while Alameda County recorded a 9.6 percent rate.
The various communities in Alameda County saw their rates drop anywhere from one-tenth to three-tenths of a point.
Castro Valley recorded a 5.5 percent jobless rate while Union City and Newark both posted 8.7 percent.
San Lorenzo listed a 6.9 percent rate while San Leandro dipped to 9.2 percent. The neighboring community of Cherryland saw its rate fall to 13.5 percent.
In the Tri-Valley, Dublin recorded a 5.6 percent rate, Pleasanton had 4.7 percent and Livermore came in at 6.1 percent.
In Contra Costa counties, communities showed either the same rate or a drop of one-tenth to two-tenths of a point.
Concord's rate was listed at 10.1 percent while Clayton recorded 2.3 percent. Neighboring Walnut Creek had a 6.3 percent rate.
In the San Ramon Valley, Danville posted a 4.9 percent rate, Alamo had 3.5 percent and San Ramon had 3.9 percent.
In Lamorinda, Lafayette stood at 3.4 percent, Moraga at 5.6 percent and Orinda at 3.5 percent.
Martinez recorded a 7.5 percent rate while Hercules came in at 6.7 percent.
California's unemployment rate was 10.9 percent in December. Nationwide, the rate was 8.3 percent.