Nonthaburi Province is found in history as a part of Krung Si Ayutthaya. In the year 1636 King Prasat Thong commanded a canal dug as a short cut from Ban Talat Khwan to the mouth of Bang Kruai Canal a total distance of five kilometers. In the year 1665 King Narai the Great gave a royal command to build a fortress at the mouth of Khlong Mae Nam Om and the township area was moved over there too. The fortress was demolished during the reign of King Rama III to reuse the bricks for the construction of Wat Chalerm Phra Kiat. In the year 1928 King Phra Pok Klao gave a royal command to relocate the township area to the present site. Nonthaburi was once consolidated with Krung Thep on January 1, 1943; however, it was re-established as an independent province again on May 9, 1946.