At the beginning of the year, Amazon launched its Go self-service convenience store in Seattle. The retail concept featured next to no staff, apart from the ones that stocked the shelves, with consumers paying for the items they pick up via an app, foregoing any interaction with cashiers.

Clearly deemed a success, now Amazon Go is expanding to two more American cities, with Chicago and San Francisco set to receive their own stores.

There is no official timeline for when the stores will open, but Amazon is reported to have already bought a location in each city, according to The Verge. The San Francisco store is said to be heading to Union Square, but the Chicago one is unknown for now.

It's still unclear what Amazon's endgame is with the Go convenience stores, whether or not it will launch its own chain of cashier-less outlets, or simply integrate the system into existing stores like Whole Foods (which it owns).