What is today the US was sparsely the population pre colonization in the first place. The native population was decimated by disease and miscegenation for the most part. But, today there are far more natives in the US than in pre columbian times bar none.
But, anyways like I said natives were far more white aligned here than anywhere else. Only the US has a "5 civilized tribes" that ran sovereign nations on the chattel enslavement of black people with the same slaves/black codes and all as the white southern states did.
Justice Taney who ruled on the Dred Scott decision even directly compared natives to black americans stating that they were free and sovereign people who could be elligible to be considered citizens while blacks were inferior people meant for subjugation thus not eligible for citizenship.
And not all natives were removed in the Trial of tears(where they brought their black SLAVES along with them in chains). Some remained in the east, but they had to give up their tribal sovereignity and adopt US citizenship.
The Mississippi Choctaw were in fact the first major non-white ethnicity to adoptain US citizenship.
Treaty of Dancing Rabbit Creek - Wikipedia
The Eastern Cherokee were granted the same option.
Treaty of New Echota - Wikipedia