british columbia is the westernmost province of canada, bordered by the pacific ocean. with an area of it is canada's third-largest province. the province is almost four times the size of united kingdom, two and one-half times larger than japan and larger than every u.s. state except alaska. it is bounded on the northwest by the u.s. state of alaska, directly north by yukon and the northwest territories, on the east by alberta, and on the south by the u.s. states of washington, idaho, and montana. formerly part of the british empire, the southern border of british columbia was established by the 1846 oregon treaty. the province is dominated by mountain ranges, among them the canadian rockies but dominantly the coast mountains, cassiar mountains, and the columbia mountains. most of the population is concentrated on the pacific coast, notably in the area of vancouver, located on the southwestern tip of the mainland, which is known as the lower mainland. it is the most mountainous province of canada.