Starting today, bitcoin is an official national currency in El Salvador, along with U.S. dollars. To use the cryptocurrency, Salvadorans need to download an electronic wallet. If they use the government-sanctioned wallet, they’ll get $30 worth of bitcoin to use. Stores have to accept bitcoin, provided they have internet access and can do so. They’ll still take American dollars. In the past six months, the value of a bitcoin has fluctuated by as much as $30,000, so how it’ll go is anyone’s guess. Marketplace’s Jed Kim speaks with George Selgin, who directs the Center for Monetary and Financial Alternatives at the Cato Institute.