On January 1, 2006 Ōhasama was merged with the town of Tōwa, from Waga District, the town of Ishidoriya, from Hienuki District, and the old city of Hanamaki to form the new city of Hanamaki (which lies to the south).
Ōhasama is itself composed of four major areas: Ōhasama (大迫）proper, which lies in the center; Uchikawame (内川目), a valley to the north; Sotokawame (外川目), to the east; and to the west is the flatter farmland of Kamegamori (亀々森).
Ōhasama lies in the mountainous region of the Kitakami River area. This results in a sharp contrast between daytime and nighttime temperatures - most noticeably in the summer. It also receives little snow or rainfall compared to surrounding areas.
The shrine at Mount Hayachine is famous for a local variety of Kagura （神楽）. Kagura dancers often appear at area festivals or functions. On a hill above the town of Ōhasama proper stands a statue resembling the wolf-like costumes donned by Hayachine Kagura dancers.
Mt. Hayachine is also home to a particular species of edelweiss, called Hayachine Usuyukisou, which grows exclusively on the mountain. It was because of this flower that mountain climbers from Ōhasama forged a friendship with those from Berndorf, Austria, resulting in the two becoming sister cities in 1965.
Around the time of Japan's Girls' Festival, Ōhasama puts on displays of its collection of dolls: many of which are several hundred years old. Local history suggests that the dolls may have been given to residents of Ōhasama by travelers from Kyoto on their way to trade in Hokkaidō.
As part of the city of Hanamaki, Ohasama is also twinned with Hot Springs, Arkansas. As of 2007, Ōhasama Junior High School has begun a sister school partnership with Jessieville Middle School in Arkansas, U.S.A. thanks to a friendship forged during a visit to Hanamaki by visitors from the Jessieville School.