Macy’s will break a 155-year-old tradition on Thanksgiving to join the race to grab shoppers on the holiday.

Macy’s officials said the first Thanksgiving Day opening in the chain’s history is in response to customer interest and is “consistent with many other retailers,” according to a media release. Experts said the move also gives the retailer a jump on a shorter than usual holiday shopping season.

Opening on Thanksgiving “becomes a competitive situation,” said Paul Swinand, a retail analyst for the Chicago-based investment research firm Morningstar Inc. If market leaders such as Wal-Mart and Target open on Thanksgiving, as they did last year, then other retailers must follow suit, he said.

“It is a zero-sum situation if everyone does the same thing,” Swinand said.

Last year, more than 35 million Americans visited retailers’ stores and websites on Thanksgiving, up 20 percent from 29 million in 2011, according to the National Retail Federation

Sears, Kmart, Toys “R” Us, Old Navy and Gander Mountain also were among the retailers who opened their area stores last year on Thanksgiving to give consumers a head-start on “Black Friday,” traditionally the busiest shopping day of the year. Macy’s, based in Cincinnati, said it will open most of its 800 stores nationwide at 8 p.m. Nov. 28.

The November-December holiday shopping season can represent as much as 40 percent of annual sales for some retailers. In 2012, holiday sales increased 3.5 percent to $579.5 billion, according to retail federation data. In comparison, 2011’s $560.2 billion was a 5.1 percent increase over 2010. On average, holiday sales have increased 3.3 percent for the last 10 years.

The retail federation is forecasting holiday season sales of $602.1 billion, an increase of 3.9 percent over 2012’s sales growth.

This year there are only 26 days between Thanksgiving and Christmas, compared with 32 days in 2012. Consumers will have four, not five, full weekends this year in that time frame.

Retailers also are expected to start their holiday promotions earlier this year because of a quirk in the calendar. The first day of Hanukkah and Thanksgiving fall on the same day this year, which hasn’t happened since the late 1800s. That means a lot of Hanukkah shopping will shift to before Thanksgiving, experts said.

Swinand said fewer shopping days often can result in lower holiday sales totals.

“More days equals more sales, but there is still only so much consumer spending to go around,” he said.

The ongoing partial government shutdown also could negatively impact consumer confidence and spending, Swinand said.

For some, the growing trend of retailers opening on Thanksgiving represents a greed-fueled encroachment on the family holiday. For others, it represents a chance to get out of the house and spend time with family in a different way.

Cathy Gloeckler of Springboro said people should be spending time with their families on Thanksgiving, rather than going out shopping. The early openings take the “true meaning” away from the holiday, she said as she exited the Macy’s store at the Dayton Mall on Tuesday.

“I think 8 o’clock in the morning on Friday is plenty early enough,” Gloeckler said.

Tulu Toros, who was in town Tuesday from Manhattan, Kan., said the Thanksgiving openings are beneficial to shoppers. “I’m sure that there would be some people who would come out,” he said.

Macy’s officials said they planned early this year to minimize the impact on store associates, who were allowed to volunteer for preferred shifts throughout the holiday season, including on Thanksgiving weekend.

Macy’s Inc. operates stores at the Dayton Mall in Miami Twp., the Mall at Fairfield Commons in Beavercreek and the Upper Valley Mall in Springfield, and has several locations in the Cincinnati area, including the Tri-County Mall and Kenwood Towne Center.