Iida is a city in Nagano Prefecture, Japan. , Iida had an estimated population of 101,536, and a population density of 154 persons per km2. The total area of the city is . Iida is an environmental model city, a municipality designated by the Japanese government to be a model for making large cuts in greenhouse gas emissions towards a low-carbon society.
Iida is the southernmost city of Nagano Prefecture. Mount Hijiri at is the highest elevation in the city. Iida lies 90 minutes northeast of the major city of Nagoya by automobile via the Chūō Expressway. The same expressway also provides access to Tokyo, about four hours to the east. The nearest large metropolis to Iida is Nagoya, which is easily accessible by bus (about 2 hours). The larger cities of Matsumoto and Nagano in central and northern Nagano Prefecture are also accessible by bus and train. There is also a bus service to Shinjuku, Tokyo, which takes about four hours.
Nagano Prefecture
Kamiina District: Iijima
Shimoina District: Matsukawa, Takamori, Achi, Shimojo, Yasuoka, Tenryū, Takagi, Toyooka, Ōshika
Kiso District: Nagiso, Ōkuwa
Shizuoka Prefecture
Shizuoka: Aoi-ku
Hamamatsu
Haibara District: Kawanehon
Iida has a humid subtropical climate (Köppen climate classification Cfa) with very warm summers and cold winters. The average annual temperature in Iida is . The average annual rainfall is with July as the wettest month. The temperatures are highest on average in August, at around , and lowest in January, at around .
Per Japanese census data, the population Iida remained relatively constant from 1960 until 2010 but has decreased slightly in recent years.
As of 2001, 1,700 people, 1.5% of the city's population, were Brazilians.
The area of present-day Iida was part of ancient Shinano Province. The area was part of the holdings of Iida Domain during the Edo period and developed as a jōkamachi surrounding Iida Castle. The town of Iida was created within Shimoina District with the establishment of the municipalities system on April 1, 1889.