This article provides a list of operational and under construction (or approved) high-speed rail networks, listed by country or region. While the International Union of Railways defines high-speed rail as public transport by rail at speeds of at least 200 km/h (124 mph) for upgraded tracks and 250 km/h (155 mph) or faster for new tracks, this article lists all the systems and lines that support speeds over 200 km/h (120 mph) regardless of their statuses of upgraded or newly built.[1][2]