Yes, although most of South America suffered in different ways that are arguably worse. The Mohawk and the Navajo retained their language and their culture; the Caribs and the Quilmes are so thoroughly effaced that we know nothing of their religion and their folklore. Nothing as culturally catastrophic as the burning of the Maya codices befell the Haudenosaunee.
Although the situation for Native Americans in the US is extremely bad and has been much worse, I think your 1%/100% contrast overstates the case a little bit. The current (not pure) Native American population in the US is 2.9%, or 9.7 million people. This may be higher than the pre-Columbian population of Native Americans, and if it's lower, it's probably not by more than a factor of three, and I really don't want to endorse ideologies proclaiming the virtues of racial purity, since I am a liberal.
The great problem is, in my outsider view, not population loss, and even less is it "race mixing", but the parlous circumstances to which modern Native Americans have been reduced --- circumstances largely established by openly white supremacist government policies.