SEATTLE (AP) -- Executives from some of Washington's largest employers on Tuesday urged Boeing Co. to build a second assembly line for its long-delayed 787 jetliner in the state, entering the fray in an interstate competition for the facility.

In a letter to Jim Albaugh, the head of Boeing's commercial aircraft unit, more than two dozen corporate leaders wrote that "we encourage you to locate that line here in Washington, where we have a long track record of demonstrable success together."

Boeing's commercial aircraft division is based in Everett, Wash. Executives at the company's Chicago headquarters are expected to select a location for the new assembly line by year's end. States seen as competitors to Washington include South Carolina, North Carolina, Kansas, Texas and California.

Labor relations are considered key to persuading Boeing to keep 787 production in the state. Boeing has indicated it wants a no-strike agreement with the International Association of Machinists union, which waged an eight-week strike last year that shut down the company's commercial airplane facilities.

"We recognize that Washington continually must improve its competitive standing in today's global economy," the executives said in the letter. "In recent years, we have made progress on a number of issues that are important to both Boeing and the rest of the business community, but agree that more work remains to be done."

They continued: "... We pledge our support to you and your entire company in working to ensure Washington remains the single best place for you to design, build and market commercial airplanes."

Boeing spokesman Bernard Choi said the company appreciated "the interests and concerns of our Puget Sound colleagues."

"We have and will continue to evaluate the many factors that would be part of a decision on a potential second line for the 787," he said in an e-mail message.

Among the executives who signed the letter were William S. Ayer, chairman and CEO of Alaska Airlines; Colleen B. Brown, president and CEO of Fisher Communications; Jeff Brotman, chairman and co-founder of Costco Wholesale, and Phyllis J. Campbell, chair for the Pacific Northwest of JPMorgan Chase.

Shares of Boeing rose 24 cents to close at $51.90.