The road to Seattle Southside began in 1999 when Katherine Kertzman was hired as the Tukwila Tourism and Marketing Director. In 2002, after the successful "Think Tukwila" branding campaign, SeaTac created an agreement with Tukwila to jointly market the two cities as a region known as Seattle Southside. Des Moines came on board in 2006. Under the name of Seattle Southside Visitor Services, the organization marketed the region as a traveler’s ideal home base to explore the Pacific Northwest.
Funding for the program came from a portion of the cities’ lodging tax funds. The Lodging Tax Advisory Committee in each city directs the spending by making recommendations to the city councils regarding its use. This body was formed to implement legislation passed by the state legislature in 1997, which directs that one percent of city taxes collected on lodging be used to promote tourism. The committee, comprised of elected officials, half hoteliers and half other tourism venues, gives the local business community a great voice.
In 2014, Seattle Southside hoteliers petitioned the cities to create a self-assessed tourism promotion area fund to increase funding for tourism marketing and promotion. Seattle Southside Regional Tourism Authority was established in 2015.