Ongkharak district

The old district office of Ongkharak was in Tambon Bang O (now in Ban Na district). In 1889 King Chulalongkorn ordered the construction of the Rangsit Canal, a canal that links the Chao Phraya and Nakhon Nayok Rivers. The water gate in the Chao Phraya River was named Chulalongkorn Water Gate (ประตูน้ำจุฬาลงกรณ์), and its corresponding gate in the Nakhon Nayok River was named Saovabha Bhongsi Water Gate (ประตูน้ำเสาวภาผ่องศรี). The district office was moved near the 16th Khlong of Khlong Rangsit. Twenty years later, the office moved to a place next to the Saovabha Bhongsi Water Gate. Now the district office is behind Saovabha Market, 500 m from the old office.^[2]
Originally, Ongkharak district was divided into seven subdistricts (tambons). In 1968, Pho Thaen (no.4) was separated from Bang Pla Kot (no.7).^[3] In 1969, Bang Sombun (no.5) was separated from Bang Luk Suea (no.8).^[4] In 1984, Chumphon (no.10) was separated from Bueng San (no.2).^[5] In 1990, Khlong Yai (no.11) was separated from Ongkharak (no.9).^[6]

Neighboring districts are (from the northeast clockwise): Ban Na and Mueang Nakhon Nayok of Nakhon Nayok Province; Ban Sang of Prachinburi province; Bang Nam Priao of Chachoengsao province; Lam Luk Ka, Thanyaburi, and Nong Suea of Pathum Thani province.

The important water resources are the Nakhon Nayok River and Khlong Rangsit.

There are thirty-three Theravada Buddhist temples in the district.
One in Bueng San, Chumphon, Khlong Yai, Pho Thaen and Phra Achan, three in Ongkharak and Sai Mun, five in Bang Luk Suae and Bang Pla Kot, six in Bang Sombun and Sisa Krabue.^[7]
In Phra Achan and Chumphon subdistricts have Muslims their eleven mosques.