Amazon is officially putting down roots in Mendocino County with a new delivery center under construction just north of Ukiah. The facility will serve as a last-mile hub, sorting packages for local delivery as part of the company’s nationwide expansion into rural areas. Amazon says the investment is aimed at faster shipping and job creation, though it has not released local hiring numbers yet. Critics, including Ukiah’s mayor, worry about worker treatment and say the project moved ahead without enough public input. Even so, the company expects the facility to be completed later this year.