I'm pretty sure this is the only answer. Those cities are where their warehouses are located, which is why they can offer same-day delivery from it. It's pretty

I'm pretty sure this is the only answer. Those cities are where their warehouses are located, which is why they can offer same-day delivery from it. It's pretty unfeasible to offer the service for a city located 150mi away from a warehouse, for instance. The cost would be too high.