Amazon has expanded their same-day delivery to some additional cities, as well as broadened the window some customers have to order items to qualify for the service.

San Francisco and Dallas are among the new cities added to the list, which now totals 12. Amazon offers same-day delivery on over one million products in Baltimore, Boston, Chicago, Dallas, Indianapolis, Los Angeles, New York City, Philadelphia, Phoenix, San Francisco, Seattle, and Washington DC.

Here’s the way Amazon’s same-day delivery service works: When you order before certain cut-off times, your items will qualify for Same Day Local Express Delivery. If the order is placed after the deadline, your order will be delivered the next business day.

So, expanding the time you have to order something to still qualify is a big deal. In places like Dallas, L.A., Phoenix, and Seattle, customers can place orders as late as 12:15 pm and still receive their packages on that same day.

Still, this expansion leaves the majority of the country in two-day shipping land. Amazon unveiled their same-day service over four years ago, and today it only exists in a dozen metropolitan areas.

The Wall Street Journal also reports that Amazon is also making it easier to locate all the items eligible for their same-day delivery service with new search filters and dedicated Local delivery page.

Speaking of Amazon and delivery, it was recently reported that the company is currently building the infrastructure for its own delivery service that would tackle the “last mile” of delivery, or the final leg. Apparently, Amazon is tired of being so dependent on UPS and FedEx.

Image via Stephen Woods, Flickr Creative Commons