Hmmm.

Most sparkling wine from the US is called sparkling wine. There does seem to be an exception:

http://blog.wine.com/2013/01/inaugural-california-champagne-controversy/

Korbel Wine Cellars began producing “California Champagne” in the late 1800s, when using the term “champagne” on wine labels outside of champagne caused no worldwide ire. They have continued to do so, even with the sale of the company, a sale that mandated continuation of the term “champagne” on the label. They are old school. They’ve been using the term for years and have no reason – or requirement by law – to change. But other wineries who produce sparkling wine in California who are “grandfathered” in do not use the term, mostly out of respect for the Champagne region. Interestingly, the majority of California sparkling wines who continue to use “California Champagne” on their labels are priced below $15. Those pricing their wines in the $30+ brand themselves as California sparkling wine. It reflects the fact that the majority of wine consumers on the market most likely do not understand the difference of Champagne and sparkling wine.