Since the inauguration of its first line in 1900, Paris's Métro network has grown to become the city's most widely used local transport system; today it carries about 5.23 million passengers daily through 16 lines, 303 stations (385 stops) and  of rails. Superimposed on this is a 'regional express network', the RER, whose five lines (A, B, C, D, and E), 257 stops and  of rails connect Paris to more distant parts of the urban area.