The United Counties of Leeds and Grenville, commonly known as Leeds and Grenville, is a county and census division in Ontario, Canada, in the Eastern Ontario subregion of Southern Ontario. It fronts on the St. Lawrence River and the international boundary between Canada and the United States, opposite of the State of New York. The county seat is Brockville. The county was formed by the union of the historical counties of Leeds and Grenville in 1850.
There are 10 municipalities in Leeds and Grenville (in order of population):
The city of Brockville and towns of Gananoque and Prescott are part of the Leeds and Grenville census division but are independent of the county.
As a census division in the 2021 Census of Population conducted by Statistics Canada, the United Counties of Leeds and Grenville had a population of living in of its total private dwellings, a change of from its 2016 population of . With a land area of , it had a population density of in 2021.
William Buell granted the land for construction of the Brockville Courthouse atop a hill rising from the Saint Lawrence River. A broad boulevard extends to the main street. One of the oldest courthouses in Ontario, it was erected in 1842. The original plan had been to build one in Johnstown Township, but the land there was too swampy. Instead, it was built in Elizabethtown Township.
The figure of Themis, a blindfolded woman holding the scales of justice, was made by master carver William Holmes in 1844. This statue was named "Sally Grant" by Paul Glasford, the chair of the building committee, in honour of the woman who posed as the model. It was erected in 1845, damaged by Hurricane Hazel in 1954 and rotting by 1956. The original is on display at a Westport museum. A replica carved by Robert Kerr of Smiths Falls was placed atop the courthouse in 1982.
Brockville is serviced by Via Rail, as well as intercity bus service. There is local public transit in Brockville, and on-demand transit in North Grenville.
Since 1832 the Rideau Canal was a major freight transport route. Since the 1960s however, it has been used exclusively for pleasure craft.
The town of Smiths Falls is mostly located in Lanark County, while parts of the southern areas of the town are in the township of Rideau Lakes in the United Counties of Leeds and Grenville.