Sai Noi is the northwesternmost district of Nonthaburi province, central Thailand.GeographyNeighboring districts are Lat Bua Luang Lat Lum Kaeo, Bang Bua Thong, Bang Yai, and the districts Phutthamonthon and Bang Len of Nakhon Pathom Province.HistoryAt first the area was administrated from Amphoe Bang Bua Thong. On January 1, 1948 four subdistricts were split off to from the new minor district Sai Noi. On June 6, 1956 it was elevated to full district status.In 1959 the Tambon Khun Si was transferred from Amphoe Bang Len (Nakhon Pathom) to become part of Sai Noi.In 1979 the southern part of Tambon Rat Niyom formed the new Tambon Khlong Khwang. The following year the southern part of Tambon Sai Noi was split off to create Tambon Thawi Watthana.AdministrationThe district is subdivided into 7 subdistricts, which are further subdivided into 68 villages . Sai Noi itself has subdistrict municipality status which covers parts of tambon Sai Noi and Khlong Khwang. There are further 7 Tambon administrative organizations .