is an administrative district of Japan

Districts of Japan

The was most recently used as an administrative unit in Japan between 1878 and 1921 and is roughly equivalent to the county of the United States, ranking at the level below prefecture and above city, town or village. As of 2008, cities belong directly to prefectures and are independent from...

 located in central Kanagawa Prefecture

Kanagawa Prefecture

is a prefecture located in the southern Kantō region of Japan. The capital is Yokohama. Kanagawa is part of the Greater Tokyo Area.-History:The prefecture has some archaeological sites going back to the Jōmon period...

. It currently consists of only one town, Aikawa

Aikawa, Kanagawa

is a town located in Aikō District, Kanagawa Prefecture, Japan. As of February 1, 2010, the town had an estimated population of 41,513 and a density of 1,210 persons per km². The total area was 34.29 km².-Geography:...

, and one village, Kiyokawa

Kiyokawa, Kanagawa

is a village located in Aikō District, Kanagawa, Japan. As of 2010, the village had an estimated population of 3,556and a density of 49.9 persons per km². The total area is 71.29 km².-Geography:...

.

History

Aikō District was one of the ancient subdivisions of Sagami Province

Sagami Province

was an old province in the area that is today the central and western Kanagawa prefecture. It was sometimes called . Sagami bordered on Izu, Musashi, Suruga provinces; and had access to the Pacific Ocean through Sagami Bay...

, extending from central Sagami north to the border of Musashi Province

Musashi Province

was a province of Japan, which today comprises Tokyo Prefecture, most of Saitama Prefecture and part of Kanagawa Prefecture. It was sometimes called . The province encompassed Kawasaki and Yokohama...

 between the Sagami River

Sagami River

The is a river in Kanagawa and Yamanashi Prefectures on the island of Honshū, Japan.The upper reaches of the river in Yamanashi prefecture are also sometimes known as the , and the portion near the river mouth as the...

 and the Tanzawa Mountains. The district offices were located in what is now part of Atsugi

Atsugi, Kanagawa

is a city located in central Kanagawa Prefecture, Japan. As of 2010, the city has an estimated population of 225,622 and a population density of 2,410 persons per km². The total area was 93.83 km²...

. The area was part of a vast shōen

Shoen

A was a field or manor in Japan. The Japanese term comes from the Tang dynasty Chinese term zhuangyuan.Shōen, from about the 8th to the late 15th century, describes any of the private, tax-free, often autonomous estates or manors whose rise undermined the political and economic power of the...

controlled by the Oe clan

Oe no Hiromoto

Ōe no Hiromoto was a kuge and vassal of Japan's Kamakura shogunate, and contributed to establishing the shogunate's governmental structure....

, and their descendents, the Mōri clan

Mori clan

The Mōri clan was a family of daimyō, descended from Ōe no Hiromoto and established themselves in Aki Province. Their name was derived from a shōen in Mōri, Aikō District, Sagami Province. The generation of Hiromoto began to name themselves Mōri.After the Jōkyū War, Mōri was appointed to the jitō...

 of Chōshū from the Heian period

Heian period

The is the last division of classical Japanese history, running from 794 to 1185. The period is named after the capital city of Heian-kyō, or modern Kyōto. It is the period in Japanese history when Buddhism, Taoism and other Chinese influences were at their height...

 through the Sengoku period

Sengoku period

The or Warring States period in Japanese history was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century. The name "Sengoku" was adopted by Japanese historians in reference...

. It later became a contested area between the late Hōjō clan

Late Hojo clan

The ' was one of the most powerful warrior clans in Japan in the Sengoku period and held domains primarily in the Kantō region.The clan is traditionally reckoned to be started by Ise Shinkurō, who came from a branch of the prestigious Ise clan, a family in the direct employment of the Ashikaga...

 of Odawara

Odawara, Kanagawa

is a city located in western Kanagawa Prefecture, Japan. As of 2010, the city had an estimated population of 198,466 with a population density of 1,740 persons per km² . The total area was .-Geography:...

 and the Takeda clan of Kai

Kai Province

, also known as , is an old province in Japan in the area of Yamanashi Prefecture. It lies in central Honshū, west of Tokyo, in a landlocked mountainous region that includes Mount Fuji along its border with Shizuoka Prefecture....

. In the Edo period

Edo period

The , or , is a division of Japanese history which was ruled by the shoguns of the Tokugawa family, running from 1603 to 1868. The political entity of this period was the Tokugawa shogunate....

, it was nominally part of Odawara Domain

Odawara Domain

was a Japanese domain of the Edo period, located in western Sagami Province. It was centered on Odawara Castle in what is now the city of Odawara.-History:...

, although large portions were tenryō territory controlled by the Shogun

Shogun

A was one of the hereditary military dictators of Japan from 1192 to 1867. In this period, the shoguns, or their shikken regents , were the de facto rulers of Japan though they were nominally appointed by the emperor...

 in Edo

Edo

, also romanized as Yedo or Yeddo, is the former name of the Japanese capital Tokyo, and was the seat of power for the Tokugawa shogunate which ruled Japan from 1603 to 1868...

 through various hatamoto

Hatamoto

A was a samurai in the direct service of the Tokugawa shogunate of feudal Japan. While all three of the shogunates in Japanese history had official retainers, in the two preceding ones, they were referred to as gokenin. However, in the Edo period, hatamoto were the upper vassals of the Tokugawa...

. From 1706, a branch of the Ōkubo clan

Okubo clan

The were a samurai kin group which rose to prominence in the Sengoku period and the Edo periods. Under the Tokugawa shogunate, the Ōkubo, as hereditary vassels of the Tokugawa clan, were classified as one of the fudai daimyō clans....

 in Odawara was permitted to establish the Ogino-Yamanaka Domain on a portion of the district. Other portions of the district came under control of Karasuyama Domain of Shimosa Province.

With the Meiji Restoration

Meiji Restoration

The , also known as the Meiji Ishin, Revolution, Reform or Renewal, was a chain of events that restored imperial rule to Japan in 1868...

 of 1868, Ogino-Yamanaka Domain came under the control of Shizuoka Domain

Sunpu Domain

' was a Japanese feudal domain intermittently during the Edo period. It was centered in Suruga Province, in what is now the city of Shizuoka, but at times included Kai and parts of Tōtōmi Provinces. In 1869 the domain was renamed .-History:...

, while remaining territories became part of the new Kanagawa Prefecture. With the abolition of the han system in 1871, former Ogino-Yamanaka Domain became Ogino-Yamanaka Prefecture, and subsequently part of the short-lived Ashigaru Prefecture. It merged with Kanagawa prefecture in 1876.

The new Aikō and Tsukui Districts were established in 1878. In 1889, Aikō was administratively divided into one town (Atsugi) and 16 villages. Aikawa became a town in 1940. Mutsuai village was created in 1945 from the merger of six villages. In 1955, Mutsui merged with Atsugi and two other villages to form the city of Atsugi. In 1956, Kiyokawa was created through the merger of two villages.

pre-1889	April 1, 1889	1889 - 1926	1926 - 1943	1944 - 1954	1955 - 1989	989 - Present	Present
	Atsugi town	Atsugi town	Atsugi town	Atsugi town	February 1, 1955 Atsugi city	Atsugi city	Atsugi city Atsugi, Kanagawa is a city located in central Kanagawa Prefecture, Japan. As of 2010, the city has an estimated population of 225,622 and a population density of 2,410 persons per km². The total area was 93.83 km²...
	Koayu village	Koayu village	Koayu village	Koayu village
	Tamagawa village	Tamagawa village	Tamagawa village	Tamagawa village
	Nanmori village	Nanmori village	Nanmori village	Nanmori village
	Mita village	Mita village	Mita village	June 1, 1946 Mutsuai village
	Tanasawa village	Tanasawa village	Tanasawa village
	Shimokawairi village	Shimokawairi village	Shimokawairi village
	Tsumada village	Tsumada village	Tsumada village
	Oikawa village	Oikawa village	Oikawa village
	Hayashi village	Hayashi village	Hayashi village
	Echi village	Echi village	Echi village	Echi village	July 8, 1955 merged with Atsugi city
	Ogino village	Ogino village	Ogino village	Ogino village	September 30, 1956 merged with Atsugi city
	Aikawa village	Aikawa village	April 1, 1940 Aikawa town	Aikawa town	January 15, 1955 Aikawa town	Aikawa town	Aikawa town Aikawa, Kanagawa is a town located in Aikō District, Kanagawa Prefecture, Japan. As of February 1, 2010, the town had an estimated population of 41,513 and a density of 1,210 persons per km². The total area was 34.29 km².-Geography:...
	Takamine village	Takamine village	Takamine village	Takamine village
	Nakatsu village	Nakatsu village	Nakatsu village	Nakatsu village	September 30, 1956 merged with Aikawa town
	Susugaya village	Susugaya village	Susugaya village	Susugaya village	September 30, 1956 Kiyokawa village	Kiyokawa village	Kiyokawa village Kiyokawa, Kanagawa is a village located in Aikō District, Kanagawa, Japan. As of 2010, the village had an estimated population of 3,556and a density of 49.9 persons per km². The total area is 71.29 km².-Geography:...
	Miyagase village	Miyagase village	Miyagase village	Miyagase village