The last meat purveyor in the trendy Meatpacking District operating outside of the neighborhood’s city-owned cooperative market will join the others next month when it leaves the ground floor of TF Cornerstone’s West Coast apartment building.

Weichsel Beef has been operating for 45 years at 525 West Street, at the base of a former meat refrigeration warehouse at the corner of Gansevoort Street, Sam Farella, the company’s president, said. Weichsel plans to relocate to about 7,000 square feet at 826 Washington Street in the Gansevoort Market co-op under the High Line, just a block away, on Sept. 29.

Although the number of meat wholesalers has declined from a peak of about 200 several decades ago to about nine in 2011, Farella did not expect the industry to be extinguished completely from the area. Those that remain are in the city’s Gansevoort Market, located between Washington and West streets, and Little West 12th and Gansevoort streets, on property owned by the city.

“I think it is stable now. I hope so,” Farella said. “We’ve had enough change in the last 20 years. We never thought there would be apartments above us.”

The move comes as TF Cornerstone is looking to convert the Weichsel space to 8,340 square feet of high-end retail. The property that Weichsel has long occupied sits just feet from the future entrance to the under-construction Whitney Museum, slated to open in 2015.

TF Cornerstone, through its broker Robert K. Futterman & Associates (RKF), has leased a stretch of retail space at 810 Washington Street to fashion tenants such as the clothing boutique Intermix and Swiss lingerie retailer Hanro during the past 19 months. It is offering another 9,130 square feet at 90 Gansevoort Street between Washington and West streets, which can be combined with the Weichsel space, RKF marketing materials show.

Weichsel divides quarters of beef shipped from slaughterhouses around the country into smaller cuts for restaurants such as Brooklyn’s Peter Luger Steak House, as well as hotels and supermarkets in the Tri-State area, Farella said.

In 1980, TF Cornerstone’s predecessor Rockrose, bought the building from the Manhattan Refrigerating Co. and converted the upper floors to what is now a 318-unit residential rental building.

“We are going to take down the loading dock and restore the façade and keep the [awning] and keep the cast iron, to make it similar to the retail at Intermix [at grade],” Thomas Elghanayan, chairman of TF Cornerstone, said.

He said changes to the neighborhood have been remarkable from the days in the early 1980s, when men with bloody aprons and transvestite prostitutes mingled in the early mornings in Meatpacking District bars. And real estate pricing has shifted as well.

When he bought the building, “We figured it would be just apartments. [The Washington Street frontage] was a funny space — it did not suit for retail,” Elghanayan said. “It was not at grade and the apartment rental market was better,” he said.

At that time he could earn more per square foot from an apartment renter than from a store, and so at one time they rented those as residential units. “That has flipped,” he said.

Weichsel Beef, which opened in 1954 across Washington Street, moved to its current location about 12 years later. Rockrose tried to get Weichsel to move out in the 1980s but could not.

“We had renewal options,” Farella said.

Farella first joined Weichsel’s in 1974, and over the years took on more responsibility and ultimately bought the company he now heads.

He regrets not buying a building in the now-booming district when prices were low, but it was not for lack of trying. Circa 1987 he offered $400,000 for a structure on 10th Avenue between West 13th and Little West 12th streets, but could not get a loan from his bank.

“I was told they did not want to give a mortgage on a single-user-type property,” he said, so he was not able to purchase it.