Earlier Thursday morning, the county initially announced the reopening of every area except Bolivar, advising that SH-87 and SH-124 were still being cleared of debris.
With Bolivar's reopening, Texas Department of Transportation also allowed ferry service to resume. It had been suspended late Tuesday night over storm surge dangers from the incoming storm.
Laura made landfall near Cameron, Louisiana, as a dangerous Category 4 storm.
But ahead of its arrival, mandatory evacuations were ordered Tuesday in Galveston County and for the Bolivar Peninsula.
The most recent statistics show more than 340,000 people live in Galveston County.
Earlier in the week, County Judge Mark Henry signed a disaster declaration.