Up to 3 ounces. I guess Nevada is not a zero tolerance state. In some states, if they find a single spec of cocaine on you (the size of a grain of sand), you're busted.
If it is not 0 tolerance, they may allow very small quanities of drugs, like a ciggarette filled with weed, or a doug out, or a piece of crack rock in a glass tube. Just extremely small amounts.
Or perhaps they changed their law.