The US has become the world’s epicenter for Bitcoin mining after a crackdown in China effectively eliminated the practice in the former cradle of the industry. China’s observed share of Bitcoin mining has effectively hit zero, Cambridge researchers found, but as Al Jazeera reports, there’s a strong possibility that covert mining is still happening in China, routed through virtual private networks that make it appear the computers are operating in another country. This, the researchers say, could be the reason for recent increases in the hash rate in Ireland and Germany.