Uber on Wednesday announced the expansion of UberRush, the on-demand courier service the company began testing last year in New York City. Starting today, merchants and shoppers in Chicago and San Francisco can utilize the same rapid delivery service that those in the Big Apple have enjoyed for months.

Uber recently met with members of the press to detail how the new service works.

As The Wall Street Journal explains, the ride-hailing service has developed a set of tools that allow merchants to easily transfer customer orders to Uber's online delivery system. With an order in place, an Uber courier will arrive within a few minutes either on foot, biking or driving a vehicle to pick up the package and deliver it to the customer.

Uber said it plans to charge either $5 or $7 per delivery, a fee that the merchant can pay themselves or pass along to its customers. The company charges couriers a 20 percent fee in New York and a 25 percent fee in Chicago and San Francisco.

The Journal notes that one of the major hurdles for the service will be having enough couriers on hand to satisfy demand. When that happens with its ride-sharing service, Uber increases its pricing to encourage more drivers to become available. Thus far, the delivery service doesn't offer such incentives.