The East Bay unemployment rate ticked up a tenth of a percentage point last month even though the region added 3,200 jobs.
The state Employment Development Department reported the East Bay jobless rate rose from 8.5 percent in September to 8.6 percent in October.
Alameda County's rate stayed the same at 8.6 percent while Contra Costa County's rate rose from 8.4 percent in September to 8.5 percent last month.
Cindy Sugrue, a labor market consultant for the EDD, said the main reason for the slight increase was that more people entered the labor force last month.
The East Bay work force rose from 970,400 in September to 973,600 last month. That's the largest October work force on record.
East Bay employers added 3,200 jobs in October. Education and health fields added 2,400 while government offices added 1,000 and leisure and hospitality showed a gain of 700.
Financial services and manufacturing lost 500 jobs each.
Most communities saw no change in their jobless rates.
In the San Ramon Valley, Alamo had a rate of 3.1 percent while Danville recorded a 4.4 rate and San Ramon had 3.5 percent.
In the Tri-Valley, the jobless rates were 5.6 percent in Livermore, 4.3 percent in Pleasanton and 5.2 percent in Dublin.
In the Tri-Cities region, unemployment stood at 8.1 percent in Union City, 8.0 percent in Newark and 6.2 percent in Fremont.
Castro Valley recorded a 5.1 percent rate while San Lorenzo showed 6.4 percent.
San Leandro's rate was 8.5 percent while nearby Ashland had a rate of 10.0 percent and the Cherryland community had 12.5 percent. (Note: an earlier version of this article incorrectly gave San Leandro a 6.5 percent rate.)