Macy's, America's biggest department store chain, is expanding same-day delivery to new US markets in one of the most aggressive moves by a brick-and-mortar retailer in an era dominated by Amazon.

Macy's already offers same-day delivery in eight markets, Reuters reports. By partnering with Deliv, an Uber-like startup that uses a fleet of contract drivers to pick up online orders from stores and malls, the retailer found a cost-effective way to expand.

The initial plan is to offer the service in several more markets but there may be additions later this year, and that could take it ahead of Amazon.

Amazon offers same-day delivery in 14 markets. Currently, Macy's is offering the service in Houston, San Francisco, San Jose, Seattle, Washington DC, Chicago, Los Angeles and New Jersey.

The department store company's efforts come as the "last mile" - the final portion of a package's journey that takes it from a retailer's warehouse or store to the customer's front door.

This becomes the next battleground for retailers. Macy's has one possible advantage over Amazon in that it has 886 stores in the US from which to source products against 50 fulfilment centres by Amazon.

But fast shipping is costly and most retailers who offer it currently lose money on the service, warn logistics experts. For example, analysts estimate that Amazon loses $1 billion to US$2 billion a year on its US.

Prime service, which promises delivery within anything from one hour to two days. Amazon's net shipping cost rose to $4.2 billion in 2014, up from $3.5 billion a year earlier.

Macy's spokesman Jim Sluzewski confirmed the retailer's plans to expand the service this year, but declined to give further details.

"The thing that's so perplexing about this last mile and same day is that the consumers overwhelmingly prefer free shipping over speed," said Satish Jindel, a logistics consultant and president of SJ Consulting Group.

"It's very hard to compete with Amazon, but traditional retailers have an advantage in that they already have all of their inventory in place five miles from 90 per cent of their purchasing population at their stores," said Deliv CEO Daphne Carmeli.

"Only the biggest can afford these operations," said Jarrett Streebin, the CEO of EasyPost, a shipping startup. He estimated costs per package could reach $20 or more with additional logistics processes. "Who's willing to pay the bill?" he said.