Thanksgiving is under assault.

Stores that once closed their doors in deference to the holiday are now touting Turkey Day deals starting as early as 9 p.m. Workers who should be on vacation are answering office e-mails on their smartphones. And those who plan on celebrating with a traditional dinner are finding that the cost of a bird is near its 30-year high, according to government data.

“I think we have a sort of Norman Rockwell view of Thanksgiving,” said Kit Yarrow, head of the psychology department at Golden Gate University in San Francisco. “It’s not really linked to reality for most Americans.”

Thanksgiving has long been in danger of getting subsumed by Christmas. Every year, Americans bemoan the encroachment of pine trees and presents on pilgrims and pumpkin pie, a phenomenon the retail industry calls “Christmas creep.” But for many, a line seems to have been crossed.

“RESPECT THE BIRD!!!” Doug Matthews, 49, an avid amateur chef from New Jersey, proclaimed in a blog post.

Matthews said he penned the diatribe last year when he spied Christmas candy on the shelf at a grocery store before the Halloween treats had been discounted. He took his rant to the social cooking site Allrecipes.com, where he had been posting recipes for corn muffins, carrot salad and other dishes for nearly 15 years.

The response, he said, blew him away. It spawned a Respect the Bird campaign on Facebook, and more than 2,500 have pledged this year “to not let Black Friday shopping gobble up my Thanksgiving.” Matthews said even his 6-year-old son is on board, leaning out of the family’s car window to yell “Respect the Bird!” at homes that already have their Christmas lights up.

“It was a little like Thanksgiving was getting occupied by Christmas,” Matthews said. “I didn’t want it getting overlooked.”

Angie Seaman, 42, of Hagerstown, Md., took the pledge last month. She said the campaign resonated with her because she had to work on Thanksgiving five years in a row as a manager at a craft store. This year, she plans to cook a turkey dinner, complete with stuffing and potatoes, at her home with friends.

“Every single year that I worked, people would come in and shop, and everyone would say, ‘I can’t believe you’re open on Thanksgiving,’ ” she said. “Well, we wouldn’t be open on Thanksgiving if you didn’t shop.”

Resisting the lure of Christmas bargains may be harder this year as such retailers as Wal-Mart, Toys R Us and Kohl’s open for business on Thanksgiving for the first time. Other stores, such as Macy’s, Best Buy and Target, plan to kick off the season at midnight. For customers lining up early for deals, Best Buy is planning an outdoor screening of the latest Harry Potter movie at 9 p.m. Thursday at about 120 stores nationwide, including those in Laurel and Fairfax.

But some retailers are playing defense. Photos of a sign that Nordstrom posts annually explaining why the upscale department store has yet to unveil its holiday decor went viral this year. “We just like the idea of celebrating one holiday at a time,” it reads.

Target employee Anthony Hardwick, 29, started an online revolution when he created a petition on Change.org protesting the chain’s first Black Friday midnight opening. It garnered more than 185,000 signatures.

The midnight opening, he said, meant employees had to arrive at the store at 11 p.m. Thursday, cutting into family time. The day has special significance for him: Hardwick proposed to his fiancee last Thanksgiving.

“I’m going to miss Thanksgiving with my future in-laws, and that’s not going to impress anybody,” he said.

It’s not just retail employees who will be putting in time on Thanksgiving. Although a report by the Society for Human Resource Management showed that 97 percent of businesses give employees Thanksgiving off, wired workers often continue to log hours. A poll last year by the tech firm Xobni found that half of U.S. workers who check their e-mail outside of businesses hours do so while on vacation.

For Philadelphia resident Margaret King, who runs a consumer research firm with her husband, the problem is compounded because they work from home. On Thanksgiving, King has planned some “deep thinking” for a project on life insurance. The turkey will wait until the weekend.

“With electronic communication, it’s really getting hard to see the edges of things and to preserve sort of sacred holiday space,” she said.

But even for those who clear their business calendars and stay away from shopping, Thanksgiving is not what it used to be: cheap.

An annual informal price survey by the American Farm Bureau Association, a trade group, found that the average cost of a Thanksgiving meal for 10 — turkey, stuffing, relish, peas, the works — jumped 13 percent to $49.20. Although the price per person is less than many fast-food dinners, the cost increases are hitting consumers when few are giving thanks for the state of the economy.

“Any way you slice it, I think we do expect to see people pay a little bit more for the meal this year,” said John Anderson, a senior economist at the farm bureau.

Anderson blamed soaring turkey prices for much of the increase. The cost of whole frozen turkeys reached $1.67 per pound in September, less than a penny under last fall’s record high, before dipping slightly last month. Since the beginning of the year, prices have jumped 15 percent.

Turkey analysts said limited production and strong demand have driven up the price of the gobbler and its parts, but Americans aren’t the ones increasingly eager to wield the carving knife. The fastest growing market, they said, is Mexico.