Nope, Sioux City is the plain old garbage the rest use "Purified carbonated water, pure cane sugar, carmel color, citric acid, sodium benzoate (as a preservative), natural and artificial flavor" The Maine stuff says it's cloves and wintergreen with no mention of sassafras root. "The flavor in sassafras, safrole, has been banned by the FDA as a likely carcinogen." so it's illegal to sell the real deal in America.You can still buy Sarsaparilla here and there.
Here's a quick search result:
http://maineroot.com/sodas/sarsaparilla/
http://www.beveragesdirect.com/Sioux-City-Sarsaparilla-6-Pack.aspx?afid=15&gclid=CIGx75C2-MACFU1cfgod8YoAeQ