Walmart expands same-day grocery delivery across U.S.

Walmart is expanding its same-day online grocery delivery service to more than 40% of U.S. households, or 100 metro areas, by year-end as it tries to keep pace with online leader Amazon.com.

The service is currently available in six markets.

Tom Ward, vice-president of Walmart's digital operations, says the retail giant is powering the expansion of its same-day delivery service using its online grocery pickup program. That service uses personal shoppers to select items and then take them to shoppers' cars parked at the curb.

So far, Walmart offers curbside grocery pickup at 1,200 stores and plans to accelerate the rollout to 2,200 by year-end. It's currently using 18,000 personal shoppers.

Walmart says it will continue to use ride-hailing services such as Uber to deliver the goods to shoppers' homes as it expands its service.

READ: Walmart testing Uber, Lyft for online grocery delivery

Shoppers pay a flat fee of $9.95 but are required to spend at least $30 per order.

Ward notes that Walmart is learning from its delivery services in such countries as China and the United Kingdom.

In Canada the retailer offers grocery home delivery in regions of Toronto, Mississauga and Etobicoke, and recently partnered with SPUD for delivery in the Vancouver area.

Amazon's purchase of Whole Foods Market last year has raised the stakes in the highly competitive grocery delivery wars. Amazon recently added free two-hour Whole Foods delivery to six cities including Atlanta, Dallas and Cincinnati for its Prime members who pay $99 a year.

Meanwhile, grocery startup Instacart has been expanding its roster of clients including B.J.'s and Kroger.