I grew up in the US and (unfortunately) this was the first time I'd heard of such a concept. I did some research and "prison furloughs" became a key political issue in the 1988 US presidential election [1]. The federal prison system now only allows non-emergency furloughs for inmates if they are within 2 years of their release/parole date, and who did not commit a violent crime.
Prison furlough programs existed in all 50 states in the 1980s, and "almost 10 percent of state and federal prisoners received a furlough in 1987". [2][3]