Brome County, is an historical county of Quebec. It takes its name from the name of a manor in the parish of Barham in Kent, England that was named after the broom plant. It was named by English surveyors to one of the townships that is now in the county. The county was formed in 1855 from parts of Stanstead , Shefford and Missisquoi counties. The county is located in the Eastern Townships, one of the 12 regions of Quebec. The county lies on the foothills of the Appalachian Mountains, such that its eastern half is rolling countryside while its western half is part of the Richelieu River plains. The county is roughly an upside down odd "L" shape, bound on the south by the Canadian-American border (along 45 degrees N for 17,5 km from 72 degrees W 15 ' in Lake Memphremagog to 72 degrees W 41,5'), in the east by in part Lake Memphremagog and Stanstead County, in the north by Shefford County (45 degrees N 20' for 48 km from 72 degrees W 15' to 72 degrees W 52') and in the west by Rouville and Missisquoi counties. A small part of the northern border at the county's northeastern corner is the Township of Orford in Sherbrooke County . On the other side of its eastern border and across from Lake Memphremagog in Stanstead County are, from north to south, the full western borders of the Township of Magog and the Township of Stanstead . On the other side of its southern border is the State of Vermont and the full northern borders of the Township of Newport, the Township of Troy and the Township of Jay, all 3 in Orleans County, and most of the northern border of the Township of Richford in Franklin County. On the other side of its northern border is the full southern border of Shefford County, with the full southern borders of, from east to west, the Township of Stukely , the Township of Shefford , and the Township of Granby . To the west is Rouville County which is divided along secular parish lines, and from south to north, the Township of Saint-Armand and the Township of Dunham in Missisquoi County. The smaller pocket of the "L" is bound in the north by the Township of Granby, to the west from north to south by Rouville County (divided in secular parishes) and the Township of Farnham in Missisquoi County, a sliver of the border to the Township of Stanbridge and the full northern border of the Township of Dunham. The county is divided fully into 5 townships, 3 in the north and 2 in the south. The 3 townships in the north are, from east to west, the Township of Bolton , the Township of Brome and the Township of Farnham . The 2 southern townships are the Township of Potton in the east and the Township of Sutton in the west. The county seat is Knowlton in the Township of Brome. Notable physical features of the county include the smaller Mount Brome in the northwestern corner of the Township of Brome and the much larger Mount Sutton in the Township of Sutton, and Brome Lake in the eastern part of the Township of Brome, which flows into the Yamaska River , site of a famous duck farm. Along Lake Memphremagog in the Township of Potton are 3 mountains, from north to south, Mount Sugar Loaf , the larger Mount Owl's Head , and Mount Bear . All of these mountains in the county are well known ski hills.

In the early 1980's the county was abolished and the western half of the county was transferred to the new Regional County Municipality of Brome-Missisquoi and the eastern half was transferred to the Regional County Municipality of Memphrémagog. A Small part in the northwest were transferred to the Regional County Municipality of La Haute-Yamaska.