Google Express, the online advertising company’s home-delivery shopping service, will begin operating across New England this week as part of a national expansion expected to cover the entire United States by year’s end, the company said.

The broader delivery area means Google Express will be available to 70 million more people in the Northeast, Google said. Express is now available to roughly three-quarters of the country, general manager Brian Elliott said.

Google, a unit of technology holding company Alphabet Inc., began offering Express in the Greater Boston area in 2014, allowing shoppers to order same-day delivery of goods from retailers such as Staples, Walgreens, Babies R Us, Costco, and Guitar Center.

Same-day deliveries aren’t available across the expanded territory, which includes rural and suburban areas, where such quick turnaround times aren’t feasible. Instead, those shoppers can schedule next-day or two-day delivery, Elliott said.

“Same-day is great, but it only hits major metropolitan areas, which are already pretty well served,’’ Elliott said.

Google Express charges fees for ­delivery, starting at $5. Shoppers can buy a membership for $95 per year to waive many of those fees. Stores also require minimum purchases — often $15, but as high as $35, said Google — or may charge an additional $3 fee for small orders. Prices are set by the ­retailer and are typically the same as those charged in stores, Elliott said.

Google’s growing interest in local retail comes amid broader growth in fast-delivery options from online companies, either selling goods from their own warehouses or offering add-on services for existing retailers.

Amazon.com Inc. is growing its network of shipping centers and expanding coverage of services such as its online grocery AmazonFresh. And San Francisco-based Instacart offers online shopping and delivery for a growing list of retailers around the country, including Whole Foods, Market Basket, and Petco in the Boston area. FreshDirect, a 17-year-old company, recently announced it had raised $189 million from investors.

Google has tweaked some details of the shopping service since it first launched. The company began testing fresh-grocery delivery earlier this year, for example, but backed away from that option in subsequent months as it sought to expand Express around the country.

Today, Google Express offers unrefrigerated grocery items — spaghetti sauce, canned soup, marshmallows, and the like — along with apparel, cosmetics, home decor, toys, and other assorted consumer goods.

In addition to consumer fees, Google collects a percentage of each order, which it declined to disclose, from retailers as compensation for generating online orders. In-store ­employees use Google’s software to ­receive and compile orders, and Google hires courier and delivery ­companies to drive the shipments to customers.

“It’s a lot of folks who are already driving trucks, and we’re adding volume,’’ Elliott said.

Curt Woodward can be reached at curt.woodward@globe.com. Follow him on Twitter @curtwoodward.