<P> The 49th parallel north is a circle of latitude that is 49 ° north of Earth's equator . It crosses Europe, Asia, the Pacific Ocean, North America, and the Atlantic Ocean . </P> <P> The city of Paris is about 15 km (9 mi) south of the 49th parallel and is the largest city between the 48th and 49th parallels . Its main airport, Charles de Gaulle Airport, lies on the parallel . </P> <P> Roughly 3,500 kilometres (2,175 mi) of the Canada--United States border was designated to follow the 49th parallel from British Columbia to Manitoba on the Canada side, and from Washington to Minnesota on the U.S. side, more specifically from the Strait of Georgia to the Lake of the Woods . This international border was specified in the Anglo - American Convention of 1818 and the Oregon Treaty of 1846, however the border as indicated by survey markers placed in the 19th century deviates from the 49th parallel by tens of meters . </P> <P> From a point on the ground at this latitude, the sun is above the horizon for 16 hours, 12 minutes during the summer solstice and 8 hours, 14 minutes during the winter solstice This latitude also roughly corresponds to the minimum latitude in which astronomical twilight can last all night near the summer solstice . Slightly less than 1 / 8 of the Earth's surface is north of the 49th parallel . </P>

49th parallel is the boundary line between which two nations