Simanjiro District is one of the six districts of the Manyara Region of Tanzania.
It is bordered to the north by Arusha Region, to the north east by Kilimanjaro Region, to the south east by Tanga Region, to the south by Kiteto District, to the south west by Dodoma Region and to the west by Babati Rural District.
The district headquarters are located in Orkesumet. According to the 2012 Tanzania National Census, the population of Simanjro District was 178,693
The 2012 Tanzanian Census reported that the district had a population of 178,693, with an average household size of 4.6 people.
The 2002 Tanzanian Census reported that the district had a population of 141,676, with an average household size of 4.3 people.
Many of the district’s inhabitants are ethnic Maasai. Many of the district’s Maasai population are illiterate, have no formal education, and are practicing Christians.