Sejny County
{{Infobox settlement
| name = Sejny County
| native_name = Powiat sejneński
| settlement_type = County
| total_type = Total
| image_flag = POL powiat sejneński flag.svg
| image_shield = POL powiat sejneński COA.svg
| image_map=POL powiat sejneński map.svg |map_caption=Location within the voivodeship
| subdivision_type = Country
| subdivision_name = {{POL}}
| subdivision_type1 = Voivodeship
| subdivision_name1 = Podlaskie
| area_total_km2 = 856.07
| population_total = 20,002
| population_as_of = 2019
| population_density_km2 = auto
| population_urban = 5286
| population_blank1_title = Rural
| population_blank1 = 14716
| coor_pinpoint = Sejny
| coordinates = {{coord|54|7|N|23|22|E|region:PL|display=inline,title}}
| seat = Sejny
| parts_type = Gminas
| parts = Total 5 (incl. 1 urban)
| p1 = Sejny
| p2 = Gmina Giby
| p3 = Gmina Krasnopol
| p4 = Gmina Puńsk
| p5 = Gmina Sejny
| blank_name = Car plates
| blank_info = BSE
| website = http://www.powiat.sejny.pl/ }}
__NOTOC__
Sejny County ({{langx|pl|powiat sejneński}}) a unit of territorial administration and local government (powiat) in Podlaskie Voivodeship, in the extreme north-east of Poland, on the border with Lithuania and Belarus. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat and only town is Sejny, which lies {{convert|112|km|mi|0}} north of the regional capital Białystok.
The county covers an area of {{convert|856.07|km2|sqmi|1}}.
As of 2019 its total population was 20,002,{{Cite web|last=GUS|title=Population. Size and structure and vital statistics in Poland by territorial division in 2019. As of 30th June|url=https://stat.gov.pl/en/topics/population/population/population-size-and-structure-and-vital-statistics-in-poland-by-territorial-division-in-2019-as-of-30th-june,3,26.html|access-date=2020-09-14|website=stat.gov.pl|language=en}} with Lithuanians comprising 20.2% (4,271) of the inhabitants.{{cite web |title=Mniejszości narodowe i etniczne oraz społeczność posługująca się językiem kaszubskim wg powiatów w 2011 r. (2011 Census data) |url=http://mniejszosci.narodowe.mswia.gov.pl/mne/mniejszosci/wyniki-narodowego-spis/7990,Mniejszosci-narodowe-i-etniczne-oraz-spolecznosc-poslugujaca-sie-jezykiem-kaszub.html|website=mniejszosci.narodowe.mswia.gov.pl |publisher=Ministry of Interior and Administration |access-date=2 June 2018 |language=pl}}
Neighbouring counties
Sejny County is bordered by Augustów County to the south and Suwałki County to the west. It also borders Lithuania to the north-east and Belarus to the east.
Administrative division
The county is subdivided into five gminas (one urban and four rural). These are listed in the following table, in descending order of population.
| width="60%" border="2" cellpadding="3" cellspacing="0" style="font-size:90%;line-height:120%;" |
| bgcolor="F0F8FF"
| style="text-align:center;"|Gmina | style="text-align:center;"|Type | style="text-align:center;"|Area | style="text-align:center;"|Population | style="text-align:center;"|Seat |
| Sejny
|urban | style="text-align:right;"|4.5 | style="text-align:right;"|5,286 | |
| Gmina Puńsk
|rural | style="text-align:right;"|138.4 | style="text-align:right;"|4,164 |
| Gmina Sejny
|rural | style="text-align:right;"|218.0 | style="text-align:right;"|4,028 |Sejny * |
| Gmina Krasnopol
|rural | style="text-align:right;"|171.6 | style="text-align:right;"|3,810 |
| Gmina Giby
|rural | style="text-align:right;"|323.6 | style="text-align:right;"|2,714 |Giby |
| colspan=5 style="text-align:right;font-size:90%"|* seat not part of the gmina |