NEW YORK (AP) -- The nation's retailers boosted holiday hiring to the highest level in six years despite worries about the economy, Superstorm Sandy, and the presidential election, according to an analysis of government job data by a leading outplacement consultancy.

Between Oct. 1 and Dec. 31 retailers added 728,300 jobs, 10.3 percent more than the same three-month period in 2011, when merchants added 660,200 extra workers, according to Chicago-based Challenger, Gray & Christmas. The retail jobs added for the holiday 2012 season marks the strongest year-end hiring surge since 2006, when employment in the retail sector increased by 746,900.

John A. Challenger, CEO of Challenger, Gray & Christmas, said that holiday hiring in the retail industry was "remarkable" for a several reasons.

"More people are working, but many are still under-employed, and as a result, wages have remained stubbornly low," he said in a statement. "So spending power this year was not necessarily greater than a year ago. Additionally, more people are shopping online, where increased holiday demand is more easily met without adding a lot of seasonal workers. Yet, despite these factors, brick-and-mortar retailers moved forward with increased hiring."

Much of the holiday hiring occurred in October and November when retailers added 149,600 jobs and 490,400 workers, respectively. Merchants hired 88,300 workers in December, down from the 147,600 hired in December 2011. Challenger noted that the move by stores to officially usher in the holiday season earlier on Thanksgiving Day, instead of Black Friday, added to the early hiring surge.

The November-December period is the most important period for retailers and accounts for as much as 40 percent of their annual revenue. After a discount-fueled buying spree over the Thanksgiving weekend, sales limped along before surging in the last few days before Christmas. That was boosted by stores ramping up discounting in the final stretch.

According to the International Council of Shopping Centers tally of 20 retailers, including Macy's (M -2.68%) and Target (TGT 1.03%), stores open at least a year saw revenue for the combined months of November and December rise 3.1 percent. That's roughly on par with the 3 percent rise that the mall trade group predicted. The figure is considered a key indicator of a retailer's health because it excludes stores recently opened or closed.