NEW YORK (AP) — Amazon is hiring 6,000 full-time workers to staff up across its more than 50 distribution centers in the U.S., including centers in Murfreesboro and Chattanooga.

The workers will pick, pack and ship products to fulfill customer orders. Currently Amazon has about 50,000 full-time workers at the centers.

Amazon has been opening distribution centers across the country in order to speed up delivery times. Its $99 annual Prime membership service comes with free two-day delivery on many items.

The Seattle-based company employed about 154,100 full-time and part-time workers in total at the end of 2014.

Amazon in general has been expanding its Prime program's offerings in an effort to grow its membership with services such as grocery delivery, one-hour delivery in some cities, beefed up video streaming and the creation of a Bluetooth speaker called the Echo that syncs with Prime music.