With online food shopping options available to U.S. consumers multiplying, online shoppers are finding sustenance on the web.

31% of U.S. consumers purchased food online in the first half of the year, according to a Harris Poll of nearly 2,000 consumers taken via phone surveys in mid-June. When excluding consumers who said they didn’t buy anything online during that period from certain categories Harris asked about, 45% of U.S. consumers purchased food online during the first half of 2016.

Breaking down respondent data, the Harris Poll found online food shoppers are more likely to be millennials, with 36% of 18-34-year-olds saying they had purchased food online in the first half of the year. Online food shoppers also were more likely to be college graduates (35%), parents (37%), live in an urban area (38%) and earn at least $50,000 annually. Consumers earning less than $50,000 were less likely to have bought food online (27%) than higher-income shoppers.

Snacks were the most commonly purchased foodstuff shopped online, with 20% of U.S. consumers saying they’d bought them online, followed by non-alcoholic beverages (17%), dry packaged goods (16%), fresh fruit and vegetables (16%), meat and seafood (15%), dairy products (15%), condiments/dressings (14%), confectionary products (14%), canned goods (14%), frozen foods (12%) and baking products (12%).

More than half—52%—of those who shopped for food online said they went online to find foods they can’t find during routine grocery trips. 24% say they’ve cut down on the trips they take to the supermarket as a result of shopping online and 5% say they’ve replaced all routine grocery shopping trips with web shopping.

Investment banking firm Morgan Stanley estimates consumers will spend more than $42 billion on groceries online this year, up 163% from $16 billion in 2015. According to U.S. Commerce Department retail sales figures, U.S. consumers spent roughly $690.4 billion at food and beverage stores last year. Using that as a base and the Morgan Stanley estimates, Internet Retailer estimates U.S. consumers spent 2.3% of their food budgets online last year—a percentage that may grow to more than 6% this year.

Plenty of web-only e-retailers—and increasingly supermarket chains—are hoping to capture consumers’ food budgets with services and unique products. Amazon.com Inc., for example, began selling multiple varieties of baby food and coffee beans under the brand names Mama Bear and Happy Belly, respectively, last month. The brands are Amazon’s first venture into private-label food products. Amazon, No. 1 in the Internet Retailer 2016 Top 500 Guide, also operates Prime Pantry, which sells shelf-stable grocery and household products to Prime members, and AmazonFresh, which includes chilled and frozen products for home delivery. Amazon last month added Boston to the list of U.S. areas where AmazonFresh is available. AmazonFresh is available in eight U.S. markets, up from six a year ago.

Thrive Market, meanwhile, this week announced it had raised $111 million in its latest funding round, bringing its total raised to $141 million since launching in November 2014. The natural foods e-retailer, No. 547 in the Internet Retailer 2016 Second 500, generated $50 million in sales last year. It is on pace to generate $130 million in 2016, says co-founder and co-CEO Nick Green. (Learn more about Thrive Market in this Internet Retailer magazine profile of the company from the March 2016 issue.)

Major supermarket chains have been expanding the geographic reach of their e-grocery services as well, giving shoppers more options to buy online for curbside pickup. For example, Kroger Co. (No. 83), will add its buy online, pickup curbside offering ClickList to 20 stores in Dallas and Houston this summer. And last month Walmart.com (No. 4), rolled out its e-grocery services, called Walmart Grocery, to stores in and around El Paso, Texas; Baton Rouge, La.; and New Orleans. Walmart Grocery is now available in well over 30 metropolitan areas in the United States. A year ago, it was available in five.

Several online-only food retailers were also among the fastest-growing e-retailers last year, based on year-over-year sales growth. NakedWines.com Inc. (No. 322), Boxed Wholesale (No. 405) and Blue Apron Inc. (No. 231) are among the top 25 fastest-growing e-retailers in the Top 500 Guide.