De Tocqueville was visiting a country that had already been purged of key dissenting voices. When the American Revolution broke out, society was quite split on whether to remain a colony or to rebel. The revolutionaries won in large part by burning down loyalists' houses and tarring and feathering them, until they either fled to Canada and the West Indies or kept their mouths shut from fear. Saying that the independent US was so great because Tocqueville thought it free and prosperous is like saying any repressive state is so great because when you traveled there you met so many happy people and did not see anything amiss.

If you like contemporary primary sources, there are plenty of letters and diaries documenting how oppressive the revolutionaries were. No surprise that doesn't get covered in American schools, it would get in the way of constructing a national mythology like every newly independent nation wants to do (my own Eastern European country is just as bad).