It had nothing to do with yoga, it was a world's fair, called "A-Y-P Exposition", for Alaska - Yukon - Pacific, intended to promote trade.
Alaska was a foreign country then. A 300 pound President Taft opened the fair by telegraph from Washington DC. Not very many people had cars. There were no TV's. Washington had only been a state for 20 years. People worked 59 hours a week for 50 cents an hour. Women couldn't vote and minorities were suppressed.
Hey, cool topic about my home town. From the shreds of information I can dredge up from my memories of Washington State history classes in Junior High, I seem to remember that the Gold Rush in the Yukon pretty much put Seattle on the map because that was the starting point for all the miners on their way up to the Yukon.
I live in Japan now with my wife, so it is nice to read about Seattle again.