On February 21, 2002 the cities of SeaTac and Tukwila signed a three-year Interlocal Agreement for the purposes of promoting tourism on the Southside, and each city currently contributes $365,000 annually to the effort from their hotel/motel tax fund. In January 2005 the City of Kent also joined the partnership and signed a three-year Interlocal Agreement with Seattle Southside Visitor Services. The City of Kent currently contributes $100,000 annually to the program. Nearly all of our funding comes from the cities.

"Our three cities individually have alot to offer the visitor, but together, we have an increased ability to stimulate potential tourists’ interest and desire to visit us," said Tukwila Mayor Steve Mullet. "We complement one another extremely well," said Frank Hansen, SeaTac's mayor and chair of that city's Hotel Motel Tax Advisory Committee. "Whereas SeaTac has the lion's share of guest rooms, meeting facilities and the airport, Tukwila is an important regional center for retail shopping, dining, and family entertainment. Tukwila has more than 5 million square feet of retail shopping, world famous Museum of Flight, eight-acre Family Fun Center, golf, movie theater, and much more. And now with the additon of kent to the partnership, Seattle Southside is quietly becoming a convernene zone for sporting events. When it comes to winning bids on national sporting tournaments, the area has really been hitting home runs."

In January 2006, the City of Des Moines came aboard as Seattle Southside's fourth contributing city.  They contribute 100% of their lodging tax dollars to the program and represent four lodging establishments.