How did the *old* meanings of "liberal" and "conservative" switch around?

A long time ago, "liberal" used to mean doing what you choose as you see fit, not caring what the people in charge tell you, and "conservative" used to mean living simply, cautiously and carefully, using few resources. When did it switch, where "conservatives" are more likely to drive giant trucks use as many resources as they can ("because global warming is a lie and it is anti-American to do anything else" ) and liberals buy hybrid cars and worry about how much cardboard they use ("because it is everyone's responsibility to the planet")? Conservatives used to be the ones more likely to enforce censorship, and liberals used to be the ones more likely to go on seething rants against the government.