Google is expanding its U.S. online shopping and delivery service, by making overnight deliveries of retail items available in six states in the Midwest.

Google Express, which lets customers shop for items, including dry foods, from a range of retailers, is already available in more than a half-dozen cities, including San Francisco, Chicago, Boston and Washington, D.C. It includes same-day and overnight delivery of products.

But Google is branching out. The delivery service, which encompasses a variety of products, is available now in parts of Wisconsin, Michigan, Illinois, Indiana, Ohio and Iowa.

Partner retailers include Ace Hardware, Costco, Kohl's, Toys "R" Us, Treasure Island Foods and Walgreens, Google said in a blog post on Tuesday.

Google will also start testing a new fresh-food grocery delivery service in San Francisco and another U.S. city later this year, according to BloombergBusiness. Google did not immediately respond to a request for comment.

With the expansions, Google is broadening its ambitions in delivery services to better compete against rivals like Amazon and Instacart. AmazonFresh provides same-day and early morning delivery of groceries and other local products in a handful of U.S. cities. And on Tuesday, Amazon announced a restaurant delivery service in Seattle.

In addition to the Midwest, Google's Express service offers overnight delivery of products in parts of Northern California. Those products can be delivered the next day or several days after they're bought. Deliveries are made on Saturdays but not Sundays.