King County is the class of the Pacific North West, despite being in constant fear of relegation from the top league. 7 Seattle area teams merged in 1956 in an attempt to climb up the US Soccer ladder. The Kings were promoted for the 1961 season, the first stint in the top tier of US Soccer. The team's yellow and blue could be seen all around town, it was the city's first taste of top tier pro sports. They split Sick's Stadium with the Seattle Rainiers, then the Pilots in 1969. During this time, the team won the 1967 and 1970 US Open Cup. After the Pilots moved to Seattle, the team bought the stadium and turned it into a soccer stadium. It was always known for it's wacky sidelines dimensions, but at least the Kings had their own stadium. After that, County had a rough go in the ladder. Relegation in 1972, promotion in 1977. Relegation in 1982 lead to 4 league changes in 10 years. 1991 wasn't all a bad year, they went on to win the USOC as they finished 19th in the APL. Constant relegation almost always lead to promotion, giving opposing fans ammo to annoy the fans of KC. King's was promoted last in 2011, and has averaged 15th spot since then.
The yellow and blue colors influenced both the Pilots and Mariners, their owners figured that the baseball team's could seem like they have more fans if every one in the city was wearing their colors. Since the Mariners rebranded, King County was the only team in the city with those colors. Sick's Stadium now seats 27,000 fans. They have completely renovated the stadium, with press boxes and new locker rooms. The stadium still has old pillars much like Wrigley Field, but the fans still love it.