New York--Late holiday shoppers, both in the week leading up to Christmas and on the day after, boosted retail sales this year, according to ShopperTrak and The NPD Group.

Consumers spent approximately $44 billion the week ending Dec. 24, a 38 percent increase versus the previous week and a 15 percent increase versus the same week last year, according to ShopperTrak. Foot traffic was also higher, increasing 32 percent from the previous week.

The week’s increase, along with year-over-year month-to-date figures up 5 percent, signals that this December will outpace December 2010, the company said.

“Holiday shopping reached a climax last week,” Bill Martin, ShopperTrak founder, said. “With good weather in most of the country and the season coming to a close, procrastinators and bargain hunters hit the stores and gave retailers the sales lift they needed to outpace last year.”

Shoppers came out in full force the day after Christmas because it fell on a Monday for the first time in six years. ShopperTrak’s data ranks the day as fourth in foot traffic and sales for the entire holiday season, behind Black Friday (Nov. 25), Super Saturday (Dec. 17) and Friday, Dec. 23.

“December 26 was likely the last door-buster day of the season, as shoppers returned unwanted gift items and shopped for marked-down merchandise,” Martin said, adding that ShopperTrak expects a drop in sales this week as the season ends. “Retailers must continue to monitor same-store traffic to capitalize on the final week of the holiday season.”

The NPD Group released similar data in its Shopping Activity Weekly Holiday Trends report, finding that 69 percent of United States consumers went shopping at a brick-and-mortar retail store the week ending Dec. 26, compared with 68 percent the previous week. The shopping conversion rate remained stable at 68 percent.

“The stability in the conversion rate is a good sign that the holiday held its own this year,” Marshal Cohen, chief industry analyst at The NPD Group, said. “With so much of the season being front-loaded with self gifting, it would have been easy for a consumer to be tapped out and forgo some important gift shopping for those on their list. But they shopped … and showed it in their shopping conversion rates in brick-and-mortar stores.”

In addition to shopping visits increasing the week ending Dec. 26, the average amount spent per buying visit was up 5 percent from the previous week, the largest week-over-week increase since the week ending Nov. 28, including Black Friday, The NPD Group said.

Online shopping activity continued to decline, dropping to 14 percent the week ending Dec. 26 as compared to 16 percent the week before.

“‘Christmas crunch time’ gave a nice boost to brick-and-mortar stores, while online saw its usual drop off,” Cohen said. “So what does all this mean? Retailers had a nice Christmas, with a full load of shoppers, buyers and online visitors.”

Cohen said the “front-loaded holiday” this year will mean consumers will be “tapped out” after the first week in January.

“This fourth period of the holiday retail season this year, will be the place where we see the consumer pulling back,” Cohen said.