Amazon’s $1.5 billion air cargo hub in Northern Kentucky opened Wednesday, the latest effort by the e-commerce giant to connect a network of 40 sites and control all aspects of delivery as demand for speed and convenience accelerates.

The Amazon Air Hub operations, located at the Cincinnati/Northern Kentucky International Airport, will be the center of its U.S. cargo network. The hub opened after more than four years of planning and construction. Amazon said the U.S. hub will eventually operate a dozen flights per day and process millions of packages every week.

The hub is comprised of a 800,000-square-foot sortation building located on a 600-acre campus that includes seven buildings, a new ramp for aircraft parking and a multi-story vehicle parking structure.

Amazon said that eventually more than 2,000 people will be employed there. The air hub will also rely on robotics technology, specifically to robotics arms to move and sort packages and mobile drive units to transport packages across the building.

Amazon Air launched in 2016 and has grown into a network of more than 40 locations. Last year, Amazon Air launched its European air hub at Germany’s Leipzig/Halle Airport, a 215,000-square-foot facility that hosts two Amazon-branded Boeing 737-800 aircraft.

Amazon Air also has regional air hubs at airports in Texas, Puerto Rico and Florida in the U.S., and plans to expand to San Bernardino International Airport in California and Cincinnati/Northern Kentucky International Airport in 2021.