Budapest was organized into 10 districts (numbered from I to X) in 1873 after the unification of the cities of Pest, Buda and Óbuda. The districts at that time:
Buda: I, II
Óbuda: III
Pest: IV, V, VI, VII, VIII, IX, X
In the 1930s, 4 new districts were organized, numbered from XI to XIV. On 1 January 1950, 7 neighboring towns and 16 villages were annexed to Budapest by creating 9 new districts, so the number of its districts increased to 22. District IV was annexed to District V and the number IV was given to the northernmost newly merged town, Újpest. Former district borders were also partly modified but the old numbering system is still clear on the map. In 1994, Soroksár left District XX, became the newest district and received the number XXIII.
Districts
Listed below are the ordinal numbers of the 23 districts of Budapest, their official names (if there is one), and the names of the neighbourhoods within the districts. Each district can be associated with one or more neighbourhoods named after former towns within Budapest.
Buda is the hilly part on the west bank of the Danube (red cells in the table below), Districts I, II, III, XI, XII, XXII
Pest is the flat part on the east bank of the Danube (green cells in the table below). Districts IV, V, VI, VII, VIII, IX, X, XIII, XIV, XV, XVI, XVII, XVIII, XIX, XX, XXIII
Csepel is a big island in the south which barely belongs to Budapest. This part of the island is the District XXI and is also referred as Csepel.
Margaret Island is an island that is directly administered by the Municipality of Budapest (used to be part of District XIII) and is used as a recreational area
There is a third island called Óbuda Island (Óbudai-sziget) which forms parts of District III and hosts the Sziget Festival since 1993.
Angyalföld-Újlipótváros-Vizafogó ("Angel's Field - New Leopold Town - Beluga Catching Area")
120,256
13.43
8954.2
XIV. kerület
Zugló
124,841
18.13
6885.8
XV. kerület
Rákospalota-Pestújhely-Újpalota
80,573
26.94
2990.8
XVI. kerület
-
73,486
33.51
2192.9
XVII. kerület
Rákosmente
87,793
54.82
1601.4
XVIII. kerület
Pestszentlőrinc-Pestszentimre ("Saint Lawrence by Pest - Saint Emeric by Pest")
101,738
38.60
2635.6
XIX. kerület
Kispest ("Little Pest")
60,731
9.38
6474.5
XX. kerület
Pesterzsébet ("Elisabeth by Pest")
65,321
12.19
5385.5
XXI. kerület
Csepel
76,911
25.75
2985.8
XXII. kerület
Budafok-Tétény
54,611
34.25
1594.4
XXIII. kerület
Soroksár
23,641
40.77
579.8
All
Budapest
1,759,407
525.13
3350.4
Arrangement of districts
District I is a small area in central Buda (the western side), including the historic Castle. District II is in Buda again, in the northwest, and District III stretches along in the northernmost part of Buda.
To reach District IV, one must cross the Danube to find it in Pest (the eastern side), also at north. With District V, another circle begins: it is located in the absolute centre of Pest. Districts VI, VII, VIII and IX are the neighbouring areas to the east, going southwards, one after the other.
District X is another, more external circle also in Pest, while one must jump to the Buda side again to find Districts XI and XII, going northwards. No more districts remaining in Buda in this circle, we must turn our steps to Pest again to find Districts XIII, XIV, XV, XVI, XVII, XVIII, XIX and XX (mostly external city parts), almost regularly in a semicircle, going southwards again.
District XXI is the extension of the above route over a branch of the Danube, the northern tip of a long island (Csepel-sziget) south from Budapest. District XXII is still on the same route in southwest Buda, and finally District XXIII is again in southernmost Pest, irregular only because it was part of District XX until the mid-90s.
^"A fővárosi kerületek, a megyei jogú városok, a városok területe, lakónépessége és a lakások száma" [The area of districts of the capital, of the towns with county's rights, resident population and number of dwellings]. Magyarország közigazgatási helynévkönyve 2016. január 1 [Gazetteer of Hungary 1st January, 2016] (PDF). Hungarian Central Statistical Office. 2016. p. 21.