15 May

System Openings Germany
 * Ulm - 1897

UK
 * Portsmouth Street Tramways - 1865
 * Grimsby & Immingham Electric Railway - 1912

System Closures UK
 * Hastings & District Electric Tramways - [[1929
 * Dundee, Broughty Ferry & District Tramways - [[1931
 * Kirkcaldy Corporation Tramways - 1931

15 mei