Kanagawa Prefecture’s own page gives its founding date as 19 March 1868, and the same page shows that the name “Kanagawa Prefecture” did not exist until 21 September of that year. The six months and two days between those dates, a gap we worked out from the prefecture’s own table, are the clearest answer to what Kanagawa is and how it relates to Yokohama, the city that now contains the district the prefecture is named after.
The body that became the prefectural office was renamed four times in 1868
The page on the prefecture’s founding date opens by saying the question is hard to answer, because the late Edo and early Meiji years put the area through one change after another. The body that became the prefectural government was the shogunate’s Kanagawa magistrate’s office, taken over by the new government and renamed. Four changes of name followed inside a single year.
| Date | Change the prefecture’s table records |
|---|---|
| 19 March 1868 | The Kanagawa magistrate’s office becomes the Yokohama court |
| 20 April 1868 | The Yokohama court becomes the Kanagawa court |
| 17 June 1868 | The Kanagawa court becomes Kanagawa-fu |
| 21 September 1868 | Kanagawa-fu becomes Kanagawa-ken, the prefecture |
The page is explicit that this court was not a court in the present sense: it handled customs, taxation, policing and general administration as well as justice, and was in effect the forerunner of the prefectural office. It states that the prefectural history takes 19 March 1868, the day the magistrate’s office was renamed, as the founding date, while noting that opinions differ depending on whether one looks at the institution, the name or the administrative boundary. On the name, the page says plainly that 21 September 1868 is when the name Kanagawa-ken appears in history for the first time, over a territory that differed greatly from the present one.
The name is older than the prefecture by six centuries and belongs to a ward of Yokohama
The same page traces the name to a document of 1266 held at Tsurugaoka Hachimangu, in which “Kanagawa” appears as the name of one of two villages in Musashi Province. It records that the characters were also written in two other ways, and that the district in question, in Kuraki county and later Tachibana county of Musashi, is the area that is now Kanagawa Ward in Yokohama. The page describes it as a long-standing junction of land and sea routes.
The step from district name to prefecture name came with the port. The page states that the name became official through the establishment of the Kanagawa magistrate’s office in 1859, at the opening of Yokohama port, and that Kanagawa Prefecture followed in the ninth month of 1868. So the answer to whether Kanagawa and Yokohama are the same is that the prefecture is named after a place that is now one of Yokohama’s wards, and Yokohama is one of the prefecture’s 33 municipalities.
Kanagawa holds 33 municipalities, and exactly one of them is a village
The prefecture’s list of municipalities groups them into six areas. Counting the entries gives 19 cities, 13 towns and one village, a total of 33, and the village is Kiyokawa, which sits in the central area alongside six cities and the town of Aikawa. The town and village office list on the same page carries 13 town offices and one village office, which matches.
| Area | Municipalities the page lists |
|---|---|
| Yokohama | Yokohama City |
| Kawasaki | Kawasaki City |
| Yokosuka and Miura | Yokosuka, Kamakura, Zushi, Miura; Hayama town |
| Central | Sagamihara, Atsugi, Yamato, Ebina, Zama, Ayase; Aikawa town; Kiyokawa village |
| Shonan | Hiratsuka, Fujisawa, Chigasaki, Hadano, Isehara; Samukawa, Oiso and Ninomiya towns |
| Western | Odawara, Minami-Ashigara; Nakai, Oi, Matsuda, Yamakita, Kaisei, Hakone, Manazuru and Yugawara towns |
Three of the cities are divided into wards, and the ward office list on the same page shows 18 for Yokohama, seven for Kawasaki and three for Sagamihara, which is 28 ward offices by our own addition. Two ward names appear twice in that list: both Yokohama and Sagamihara have a Midori Ward and a Minami Ward, so a Kanagawa address in either of those wards is ambiguous without the city name.
What the level crossing at Kamakura, one of the four cities in the Yokosuka and Miura area, actually looks like and what the rules there are is set out separately in our piece on the Kamakura crossing.
The prefecture measures 2,416.55 square kilometres and prints its four corners
The prefecture’s geography page, updated on 4 March 2026, gives the area as 2,416.55 square kilometres as of 1 October 2025, citing Geospatial Information Authority data, and the coastline as 435 km. It sets out the four extreme points by coordinate.
| Extreme | Place | Coordinate |
|---|---|---|
| East | Ukishima-cho, Kawasaki Ward, Kawasaki | 139 degrees 47 minutes 46 seconds east |
| West | Mount Mikuni, Yamakita town, Ashigarakami county | 138 degrees 54 minutes 57 seconds east |
| South | Awasaki on Jogashima, Miura | 35 degrees 7 minutes 43 seconds north |
| North | Mount Shoto, Midori Ward, Sagamihara | 35 degrees 40 minutes 22 seconds north |
The same page places the prefecture near the centre of the Japanese archipelago, in the south-western part of the Kanto plain, with Tokyo to the north, Tokyo Bay to the east, Sagami Bay to the south, and Yamanashi and Shizuoka to the west. It describes the Keihin belt on the Tokyo Bay side as a heavily developed port district, and names Kamakura, with Kyoto and Nara, as a city holding historic sites and scenic places.
The page splits the terrain into three: mountains in the west, plain and plateau in the centre, hills and coast in the east. It calls the 1,500-metre-class peaks of the Hakone and Tanzawa massifs the roof of Kanagawa, names the Sagami and Sakawa rivers as the water supply, and lists five lakes, Ashi, Sagami, Tsukui, Tanzawa and Miyagase, as reservoirs held for water use. It also notes that Hakone and Yugawara form part of the Fuji-Hakone-Izu National Park, that Tanzawa is mountain country, and that the prefecture has four prefectural natural parks.
Snow is recorded at Yokohama on 17.7 days a year and adds up to 9 cm
The Japan Meteorological Agency’s normals for the Yokohama station, over the 30 years from 1991 to 2020, give 17.7 snow days a year against an annual total snowfall depth of 9 cm, a greatest daily snowfall of 6 cm and a deepest snow cover of 7 cm. The monthly snow-day figures are 4.9 in January, 7.0 in February, 3.4 in March, 0.1 in April and 2.3 in December, and those five add to the annual 17.7.
February carries more snow days than January even though January is the colder month, with a mean of 6.1C against February’s 6.7C. Annual precipitation on the same table is 1,730.8 mm and annual sunshine 2,018.3 hours. The all-sky solar radiation column is blank with a data-years entry of zero, and the cloud, fog day and thunder day columns rest on 29 years rather than 30, so those four are left out here.
The prefecture’s geography page quotes a different kind of figure for Yokohama: single-year values for 2025 from the Yokohama local meteorological office, giving a mean annual temperature of 17.6C, a highest temperature of 38.1C, a lowest of minus 0.6C and annual precipitation of 1,321.5 mm. That last number and the 1,730.8 mm normal are not measuring the same thing, one being a single calendar year and the other a 30-year normal; with that difference stated, the arithmetic gap between them is 409.3 mm, which is our own subtraction.
The boundary moved three times after the prefecture was named
The prefecture’s table continues past 1868. In 1871 the abolition of the domains turned Mutsuura, Ogino-Yamanaka and Odawara domains into prefectures on 14 July; Mutsuura was abolished in the ninth month and folded into Kanagawa, while Ogino-Yamanaka and Nirayama were folded into Odawara, which was renamed Ashigara Prefecture on 14 November. Ashigara Prefecture was abolished on 18 April 1876 and merged into Kanagawa. The last change the table records is 1 April 1893, when three Tama counties were separated off to Tokyo-fu, and the page states that this is the point at which the present prefectural area was fixed. Counting the table’s entries that change Kanagawa’s own territory gives three: the 1871 merger of Mutsuura, the 1876 merger of Ashigara and the 1893 separation of the Tama counties.
For a visitor the practical consequences are small but real. An address in Kanagawa is not an address in Yokohama, and within Yokohama the ward matters because two of its ward names are shared with Sagamihara. Snow is a normal part of a Yokohama winter as an event, on about 18 days, but not as a depth, with 9 cm for the whole year. And the prefecture that Kamakura, Hakone and Yokohama all sit in measures 2,416.55 square kilometres with 435 km of coastline, which is why those three are close enough to combine in a short stay.
Sources Checked
Kanagawa Prefecture — origin of the prefecture’s name and its founding day
Confirmed the 1266 document held at Tsurugaoka Hachimangu naming Kanagawa as one of two villages in Musashi Province, the two alternative writings of the name, the identification of the district with the present Kanagawa Ward of Yokohama, the Kanagawa magistrate’s office of 1859 at the opening of Yokohama port, the renaming to Kanagawa Prefecture in the ninth month of 1868, the statement that the question of a founding date is hard to answer, the court’s combined customs, taxation, policing and administrative role, the prefectural history’s choice of 19 March 1868, the four 1868 changes on 19 March, 20 April, 17 June and 21 September, the 1871 abolition of the domains with Mutsuura, Ogino-Yamanaka and Odawara on 14 July and the later mergers, the renaming of Odawara to Ashigara on 14 November 1871, the abolition of Ashigara and merger into Kanagawa on 18 April 1876, and the separation of three Tama counties to Tokyo-fu on 1 April 1893.
https://www.pref.kanagawa.jp/docs/ie2/cnt/f530001/p780104.html
Kanagawa Prefecture — position, terrain, population and weather
Confirmed the update date of 4 March 2026, the position in the south-western part of the Kanto plain with Tokyo to the north, Tokyo Bay to the east, Sagami Bay to the south and Yamanashi and Shizuoka to the west, the description of the Keihin belt on the Tokyo Bay side as a developed port district, the mention of Kamakura alongside Kyoto and Nara, the area of 2,416.55 square kilometres as of 1 October 2025 citing Geospatial Information Authority data, the coastline of 435 km, the four extreme points at Ukishima-cho in Kawasaki Ward at 139 degrees 47 minutes 46 seconds east, Mount Mikuni in Yamakita town at 138 degrees 54 minutes 57 seconds east, Awasaki on Jogashima in Miura at 35 degrees 7 minutes 43 seconds north and Mount Shoto in Midori Ward of Sagamihara at 35 degrees 40 minutes 22 seconds north, the three-part division of the terrain, the description of the 1,500-metre-class Hakone and Tanzawa peaks as the roof of Kanagawa, the Sagami and Sakawa rivers, the list of Ashi, Sagami, Tsukui, Tanzawa and Miyagase lakes as reservoirs, the Fuji-Hakone-Izu National Park at Hakone and Yugawara, the four prefectural natural parks, and the 2025 Yokohama figures of 17.6C mean, 38.1C highest, minus 0.6C lowest and 1,321.5 mm precipitation from the Yokohama local meteorological office.
https://www.pref.kanagawa.jp/docs/ie2/cnt/f530001/p780101.html
Kanagawa Prefecture — list of municipalities
Confirmed the six areas and their members, the 19 cities, 13 towns and one village, Kiyokawa village in the central area with Aikawa town, the 18 ward offices of Yokohama, the seven of Kawasaki and the three of Sagamihara, the appearance of a Midori Ward and a Minami Ward in both Yokohama and Sagamihara, and the town and village office list carrying 13 town offices and one village office.
https://www.pref.kanagawa.jp/docs/ie2/cnt/f530001/p780102.html
Japan Meteorological Agency — climate normals for the Yokohama station
Confirmed the station heading for Yokohama in Kanagawa Prefecture, the 1991 to 2020 statistical period, 17.7 snow days a year with monthly figures of 4.9, 7.0, 3.4, 0.1 and 2.3 for January, February, March, April and December, an annual total snowfall depth of 9 cm, a greatest daily snowfall of 6 cm and a deepest snow cover of 7 cm, annual precipitation of 1,730.8 mm, annual sunshine of 2,018.3 hours, mean temperatures of 6.1C in January and 6.7C in February, the blank all-sky solar radiation column with zero data years, and the 29-year statistical period on the cloud, fog day and thunder day columns.
https://www.data.jma.go.jp/stats/etrn/view/nml_sfc_ym.php?prec_no=46&block_no=47670
Last updated: September 2026
