This is a very simple question but a Google search did not provide an answer.
Basically suppose you have a map of the U.S. with states and county layers, as well as other layers like roads, etc.
I want to work with a map of only one state, with all layers (e.g. counties, roads, etc) in that state.
I remember in ArcGIS it had something to do with taking an intersection, not sure how it works in QGIS.