Three years ago, when the aerospace machinists union went on strike against Boeing, more than half of the people on the picket line were older than 50. None of the 18,000 strikers -- not a single one -- was under the age of 30.

Today, union leaders say the company is working on a new policy to cover when and where it's acceptable for newly hired young workers to skateboard in the factories.

"I'm told they're tearing up the tunnels on breaks and lunches," says Tom Wroblewski, the union's Puget Sound district president.

It's just one sign of a generational change taking place across American business. The official first baby boomer, born Jan. 1, 1946, retired in February, and as she now cashes her Social Security checks in Florida, business managers are left wondering how they're going to replace between 70 million and 80 million of her cohorts who will reach retirement age in the next few years. They will take with them decades of experience and hard-to-replace skills as they exit the workforce.

"Virtually any manufacturing company is probably likely to have this problem and is probably dealing with it as well," says Sally Hass, who has the title of transition manager at Weyerhaeuser's corporate headquarters in Federal Way. "If you're Google or high-tech, you probably don't have it."

Here in Washington, some key industries already are struggling. Timber companies in Grays Harbor County report having a hard time finding millwrights -- the skilled technicians needed to keep mill machinery running.

Across eastern Washington, longtime farming families are selling out, after their children decided profit margins were too slim to justify staying in the family business. In some cases, those farmers are selling to their Latino farmhands.

"They've been working with those farmers for 15-20 years," says Malachias Flores, a county extension agent in Yakima. "The Anglo farmers are saying, 'You've been good, you've been working hard for me. You should buy the farm.'"

And at Boeing, the soon-to-retire workers are doing their best to pass on decades of knowledge to the newcomers, says John Williamson, a 64-year-old machinist who works in Auburn. "They realize they have a good job and they want to learn."

The transition isn't always smooth, says Katie Lutz, a 24-year-old who works in the tool room at Boeing's Developmental Center south of Seattle. "It's not very exciting getting called 'kiddo' and 'squirt.' Everyone thinks you're their kid, instead of your co-worker and an equal."

Some companies are ahead of the curve when it comes to succession planning. For them, it's an issue they faced early and worked on often.

"We've actually been kind of watching this for quite a number of years," says Hass. "A few years ago, we started to dig in and do due diligence."

For a while it looked to some as if the baby boomers would be the last generation to work at Boeing. For about a decade, as the company downsized and outsourced, it all but quit hiring young people, according to leaders of the machinists union. That fueled rumors that Boeing was getting out of the airplane business.

"We've got about a 10-year gap," says Wroblewski. "From 1995 to 2005, it was very minimal."

But over the past two years, Boeing has ramped up production to meet unprecedented demand for its jets. To do this, the company has called back all the eligible workers it laid off after Sept. 11, and now it's bringing in new entry-level people -- between 75 and 125 per week.

Boeing's hiring pattern over the past decade or so has left it with "a demographic bathtub," says Richard Aboulafia, an aerospace analyst with the Teal Group in Virginia. "There is a profound gap."