Amazon.com Inc. today gave Prime another boost, giving more members of the two-day-shipping-and-loyalty program access to free same-day delivery.

The service applies to 14 metro areas in the United States, with at least one million products eligible for quick delivery. That compares with some 20 million items Amazon says are available for basic Prime two-day shipping. Consumers who are Prime members must spend at least $35 per order to receive free deliveries or pay $5.99.

“Members will discover many of the most popular items on Amazon available for same-day delivery , seven days a week, including electronics, summer reads, vacation gear and much more,” an Amazon spokeswoman says. “Members can simply look for the Prime free same-day logo on over a million items, add more than $35 of these items to their shopping cart, and then choose free same-day delivery at check out. Members can also use the new Prime free same-day check box, located in the filter menu, to find free same-day items while searching or browsing.”

The eligible metro areas are: Atlanta, Baltimore, Boston, Dallas-Ft. Worth, Indianapolis, Los Angeles, New York, Philadelphia, Phoenix, San Francisco (including Oakland), Seattle-Tacoma, San Diego, Tampa, Fla., and Washington, D.C.

Of those two cities, only San Diego and Tampa are technically new entrants to Amazon’s same-day delivery service, the spokeswoman notes. Amazon’s Prime Now service, which offers delivery of goods in as little as one hour to members of Amazon Prime for a fee of $7.99—two-hour deliveries are free—already operated in the other cities. Now Prime members who spend at least $35 and place orders by noon can receive free same-day deliveries, though they might not arrive within an hour; Amazon promises only that it will deliver such orders by 9 p.m. “Prime free same-day will also include hundreds of thousands of products from businesses of all sizes using Fulfillment by Amazon,” the spokeswoman says, referring to the program under which marketplace sellers on Amazon hire the e-retailer to handle fulfillment.

Amazon keeps adding perks to justify Prime’s $99 annual membership fee. This newest Prime feature follows Amazon’s launch earlier this month of one-hour Prime Now deliveries from Manhattan retail stores, not just from the e-retailer’s fulfilment facility there; the recent launch of Prime Stations, an ad-free streaming web radio service; and enabling Prime members on JetBlue flights access to movies, television shows and music through online streaming.

Amazon, No. 1 in the Internet Retailer 2015 Top 500 Guide, also faces fulfillment competition from such rivals as Wal-Mart Stores Inc., (No. 3), which earlier this month said it would test its own Prime-like shipping-and-loyalty program. That Wal-Mart program will cost $50 per year and provide free three-day delivery on eligible items.