Starbucks Corp. is expanding its mobile order and payment service to about 3,400 stores in 21 new states in the southern and central United States. The company launched mobile order and payment feature as a pilot in Portland, Ore. in Dec. 2014. The mobile payment feature allows Starbucks mobile app users to place their order in advance and pick it up at a selected Starbucks location. It is integrated into the Starbucks app and loyalty program. Starbucks mobile order and payment is now available on the Starbucks app for iPhone at more than 4,000 Starbucks stores. Starbucks plans to expand the program to the Android platform and all U.S. company-operated stores this year.