I- 49th parallel of latitude emantla yenza umda omde womda weCanada-United States, ukusuka kwiphondo laseManitoba ukuya eBritish Columbia kwicala laseCanada kwaye ukusuka kwiphondo laseMinnesota ukuya eWashington kwicala laseMelika.

Ukusetyenziswa kwayo njengomda kubangelwa iSivumelwano se-1818 kuqala kunye ne- Oregon Treaty ye -1846 ngoko, ngexesha likamongameli we-James Knox Polk.

Emva kokuba iUnited States ifumene iLouisiana ngo- 1803, kwavunyelwana ngokubanzi ukuba umda phakathi kwesi sizwe kunye neBritish Rupert's Land wawukunye nesahlulo esiphakathi koMlambo iMissouri kunye nezitshixo zoMlambo iMississippi kwelinye icala kunye ne- Hudson Bay basin kwelinye. Nangona kunjalo, kunzima ukucacisa ngokuchanekileyo indawo yendawo yamanzi kwindawo ethe tyaba njengombindi woMntla Melika.

Iikomiti zaseMelika nezaseBritane ezidibene emva kweMfazwe ye-1812 ukusombulula iingxabano zomda zaqaphela ukuba kuya kubakho inzondo enkulu ekuhloleni ummandla wamanzi, kwaye zavumelana ngesisombululo esilula ngo -1818 : i-49th parallel. Omabini amacala afumene kwaye aphulukana nomhlaba ngenxa yale ndibano, kodwa i-US izuze ngaphezulu kunokuba iphulukene nayo. Le ndibano yaseka umda kuphela phakathi kweLake of the Woods kunye neRocky Mountains ; ngasentshona kwezi, indibano yaseka umsebenzi odibeneyo weOregon Territory.

Nangona indibano ye-1818 yabeka umda ukusuka kwimbono ye-US kunye ne-United Kingdom, akukho sizwe sasilawula ngokukhawuleza phezu kwemimandla eyahluliweyo: ulawulo olusebenzayo lwahlala kunye nezizwe zendawo, ngokuyinhloko i- Coloured, i-Assiniboine, i-Lakota ne -Blackfeet . Ulongamo lwawo lwayekwa ngokuthe ngcembe luloyiso okanye isivumelwano kumashumi eminyaka alandelayo.

Ngowe- 1846 iSivumelwano saseOregon sahlulahlula i-Oregon Territory phakathi kweBritish North America ne-United States, sandisa umda wama-49 onxuseneyo ukuya kunxweme olusentshona nokunqumla iStrait yaseJuan de Fuca .Kule latitude, kufuphi ne-summer solstice, kunokwenzeka ukuba ukukhanya kweenkwenkwezi kungapheli ngokupheleleyo ngexesha leeyure zobusuku, ngaloo ndlela kushiya umgca omncinci wokukhanya kwelanga obonakala kwi-atmospheric kwicala elingasentla, ngexesha le-astronomical midnight.