The move comes two days after Amazon signed up more new members to its Prime loyalty program than on any single day in its history.

Days after signing up more new Prime customers than on any single day in the company’s history, Inc. expanded its Prime Now one-hour delivery service to two major Midwestern cities.

The world’s largest online retailer, No. 1 in the Internet Retailer 2015 Top 500 Guide, began offering the service to shoppers who have an Amazon Prime membership in five Chicago ZIP codes and 33 Indianapolis ZIP codes. Prime members living in those areas can opt to have select items delivered within an hour for $7.99 or two-hour delivery for free. Amazon says “tens of thousands” of items are available for Prime Now.

Shoppers can place their orders through Amazon’s Prime Now app, is which available on Apple Inc., Inc. and Android devices. This is the latest move by Amazon to expand its Prime Now efforts, which is also available in Dallas, Miami and Baltimore.

The Prime Now expansion comes two days after Amazon held  Prime Day, a 20th anniversary sale, which the company said attracted more new Prime customers in one day than any other day in the company’s history, but Amazon did not release the number of new customers for the $99 a year service.  The e-retailer said its Prime Day sales were 18% higher than Black Friday 2014.