lumber and granite quarries were important in the early economy. the island is a self-sustaining environment that operates on an honor system; however, infrastructure such as electricity is provided by national grid us. there are no bridges onto grindstone (save when the river freezes), or formal ferry services onto grindstone island. there is a community dock (the town dock in aunt jane's bay) provided for visitors on aunt jane's bay - some inlanders who live inland on the island park their vehicles along the road. there is a normal us postal service delivery route onto the island monday through saturday.