sentences:  In 1907 the act on operations of sanitary districts codified the regulations, and with the "Local Administration Act" of 1914 two levels of sukhaphiban were introduced, the "sukhaphiban mueang" for towns and "sukhaphiban tambon" for rural areas.The number of sanitary districts grew to 35 in 1935, when these however were converted into municipalities ("thesaban").New sanitary district were again established starting in 1952 by prime minister Phibun Songkhram.