They create the technical razzle-dazzle when the Rockettes take the stage for the “Radio City Christmas Spectacular.” They raise the 45-foot-high Christmas tree for “George Balanchine’s The Nutcracker.” And on New Year’s Eve, they will make the opulent ballroom set spin for the Metropolitan Opera’s new “Die Fledermaus.”

The stagehands of Local 1 of the International Alliance of Theatrical Stage Employees bring some of New York City’s most glittering stage effects to life, from the auditoriums of Lincoln Center to the theaters of Broadway. But their work comes at a steep price, even at venues where they do little more than load in orchestras and set up music stands.

Those high costs were underscored by a stagehands walkout that forced the cancellation of this season’s opening night at Carnegie Hall and called attention to the hall’s five full-time stagehands’ total yearly compensation, an average of more than $400,000 each. An examination of tax records, contracts and other documents by The New York Times found that hefty stagehand salaries at many New York nonprofit performance institutions are more widespread than was previously known.

At nine top such institutions that have contracts with Local 1, stagehands make up 36 of the 98 most highly compensated employees, or about 37 percent. The average annual total salary and benefits of those highest-paid stagehands, at places from the Metropolitan Opera to the Roundabout Theater Company, is nearly $310,000, according to the nonprofits’ most recent tax filings.