United Parcel Service Inc. will install lockers outside 300 retailers in the U.S. as the shipping giant expands it use of alternate delivery sites. The move expands UPS’s experiment with outdoor lockers at nine Chicago-area locations, which were typically placed outside of retailers and accessible around the clock. The company is working with the 7-Eleven convenience-store chain and independent stores to offer the new lockers. The program lets customers pick up packages at their own convenience while eliminating the need for UPS to make costly second and third home-delivery attempts. The rollout marks an expansion of UPS’s Access Point program, which until now generally recruited local retailers and pharmacies to receive packages and store them indoors. The company now has 8,000 such locations in the U.S. and 16,000 in Europe. “UPS Access Point lockers can be easily accessed when it fits the shopper’s schedule, giving an online retailer added value to present at checkout,” Kalin Robinson, director of the locker program, said in a statement Thursday. “The lockers enable more shoppers to enjoy the ease and simplicity of buying online.”