1% changes is quite a lot for a government. You want a slower pace of government so that it can adjust to the changes without it being too disruptive.
Even some of the biggest changes in American History were rather small but had resounding responses and consequences.
I would say that there were quite a few huge changes in American history. Apart from the Revolution, here are a few.
1. Civil War - Introducing an income tax, violating habeas corpus, introducing martial law, confiscation of property and positively, getting rid of slavery.
2. Introducing the Federal Reserve - a real revolution when it comes to monetary matters.
3. First World War - censorship, drafting people into the miltary against their will, spitting on the rights of an individual in general.
4. Prohibition - forcing people to comply with a ridiculous idea to ban alcohol, destroying a whole industry and the livelihoods of thousands, and by accident creating powerful criminal organizations.
5. New Deal - a lot of unconstitutional measures, bullying the Supreme Court into submission when it questioned them, public expenditures skyrocketed.
I agree that since the 1940s there have been no huge changes, but overall Obama's term marked some pretty significant left-wing changes such as Obamacare. This is both a huge change and a long-term one.