Bootle is a town in the Metropolitan Borough of Sefton, Merseyside, England, which had a population of 51,394 in 2011; the wider Parliamentary constituency had a population of 98,449. Historically part of Lancashire, Bootle's proximity to the Irish Sea and the industrial city of Liverpool to the south saw it grow rapidly in the 1800s, first as a dormitory town for wealthy merchants, and then as a centre of commerce and industry in its own right following the arrival of the railway and the expansion of the docks and shipping industries. The subsequent population increase was fuelled heavily by Irish migration.