The service, which started one year ago, will launch in Chicago, Boston and Washington, D.C., Tuesday, Google announced. Now more than 7 million more people can access the same-day delivery of items as diverse as flowers, cameras, books and bulk toilet paper.

The number of items customers have access to has also expanded as Google brings on more merchants, including Stop & Shop in Boston, Giant Food in D.C. and Wrigleyville Sports in Chicago.

Google’s (GOOG) same-day delivery service goes head-to-head with Amazon (AMZN), which offers both a $99 annual Prime membership for two-day shipping on numerous items, as well as a $299 annual Prime Fresh membership for same- or next-day grocery deliveries. Amazon has been expanding its Prime Fresh program and now covers three metropolitan areas with plans to reach as many as 20 more by the end of the year.

“Many people think our main competition is Bing or Yahoo,” Eric Schmidt, Google’s executive chairman, told The Wall Street Journal. “But, really, our biggest search competitor is Amazon.”

Google Express, formerly called Google Shopping Express, now delivers from 16 different merchants, from stores as big as Costco and Barnes and Noble to regional businesses like Fairway grocery stores and Palo Alto Sport Shop. Bay Area shoppers over 21-years-old can even order alcohol from various local liquor stores.

Google’s delivery service offers a membership model, which costs $95 a year or $10 a month. Members are privy to free same-day or overnight delivery on eligible orders over $15 and also have first dibs on delivery availabilities. Shoppers can also pay as they go for $4.99 per order.