Monroe County is a county in the U.S. state of New York, located along Lake Ontario's southern shore. As of 2025, the population was 750,506, according to Census Bureau estimates. Its county seat and largest city is Rochester. The county is named after James Monroe, the fifth president of the United States. Monroe County is part of the upstate Rochester, NY Metropolitan Statistical Area. The county is part of the Finger Lakes region of the state.
History
When counties were established in the province of New York in 1683, the present Monroe County was part of Albany County. This was an enormous county, including the northern part of the State of New York as well as all of the present State of Vermont and, in theory, extending westward to the Pacific Ocean. This county was reduced in size on July 3, 1766, by the creation of Cumberland County, and further on March 16, 1770, by the creation of Gloucester County, both containing territory now in Vermont.
On March 12, 1772, what was left of Albany County was split into three parts, one remaining under the name Albany County. One of the other pieces, Tryon County, contained the western portion (and thus, since no western boundary was specified, theoretically still extended west to the Pacific). The eastern boundary of Tryon County was approximately five miles west of the present city of Schenectady, and the county included the western part of the Adirondack Mountains and the area west of the West Branch of the Delaware River. The area then designated as Tryon County now includes 37 counties of the State of New York. The county was named for William Tryon, colonial governor of New York.
In the years prior to 1776, most of the Loyalists in Tryon County fled to Canada. In 1784, following the peace treaty that ended the American Revolutionary War, the name of Tryon County was changed to Montgomery County in order to honor the general, Richard Montgomery, who had captured several places in Canada and died attempting to capture the city of Quebec, replacing the name of the hated British governor.
In 1789, Ontario County was split off from Montgomery. The actual area split off from Montgomery County was much larger than the present county, also including the present Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston, Monroe, Niagara, Orleans, Steuben, Wyoming, Yates, and part of Schuyler and Wayne counties.
Genesee County was created by a splitting of Ontario County in 1802. This was much larger than the present Genesee County, however. It contained the present Allegany, Cattaraugus, Chautauqua, Erie, Niagara, Orleans, Wyoming, and portions of Livingston and Monroe counties.
Finally, Monroe County was formed from parts of Genesee and Ontario counties in 1821.
Geography According to the U.S. Census Bureau, the county's total area is , of which is land and (52%) is water.
Monroe County is in Western State of New York's northern tier, northeast of Buffalo and northwest of Syracuse. The northern county line is also the state line and the border of the United States, marked by Lake Ontario. Monroe County is north of the Finger Lakes.
Adjacent counties Wayne County - east Ontario County - southeast Livingston County - south Orleans County - west Genesee County - southwest
Major highways
New York State Route 15 New York State Route 15A New York State Route 18 New York State Route 19 New York State Route 31 New York State Route 31F New York State Route 33 New York State Route 33A New York State Route 36 New York State Route 64 New York State Route 65 New York State Route 96 New York State Route 104 New York State Route 153 New York State Route 250 New York State Route 251 New York State Route 252 New York State Route 259 New York State Route 286 New York State Route 390 New York State Route 404 New York State Route 441 New York State Route 531 New York State Route 590 Lake Ontario State Parkway
Government and politics Monroe County was chartered as a municipal corporation by the New York State Legislature in 1892 and rechartered under New York's Municipal Home Rule Law in 1965.
From 1856 to 1932, Monroe County voters voted for the Republican candidate in every presidential election apart from 1912. Democratic candidate Woodrow Wilson was able to win the county in 1912 when the Republican vote was divided between then incumbent president William Howard Taft and former president Theodore Roosevelt. Monroe County voted for incumbent Democratic presidents Franklin D. Roosevelt (1936, 1940, 1944) and Harry S. Truman (1948). From 1952 to 1976, Monroe County voted for the Republican candidate in all presidential elections except for Lyndon B. Johnson's Democratic landslide in 1964. In 1980, incumbent Democratic president Jimmy Carter won Monroe County, despite having lost in the county to Republican Gerald Ford in 1976. Monroe County went back to voting Republican in 1984 and 1988, but has voted for the Democratic presidential candidate every time from 1992 onwards, including the 2024 election. In 2020, Joe Biden received the highest percentage of the vote for a Democrat since Lyndon Johnson's 1964 landslide.
In recent years, the urban area's traditional partisan dynamic appears to have begun shifting in the Democratic Party's favor at the local level. A Democrat won the 2017 race for county sheriff for the first time in decades, in 2019 Democrat Adam Bello was elected county executive after over 30 years of Republican control, in 2020 democrats Samra Brouk and Jeremy Cooney flipped state senate districts long held by the GOP, and the traditionally Republican county legislature is now split 18-11 in favor of the Democratic Party. This matches a broader national trend of increased Democratic success in suburban areas.
Executive branch The county's executive branch is headed by the county executive, Adam Bello. The executive's office is on the first floor of the county office building on West Main Street in Rochester. The county clerk is Jamie Romeo, a Democrat.
The county was exclusively governed by a board of supervisors for the first 114 years of its history. In 1935, the position of county manager, appointed by the board, was approved by popular referendum. In 1983, the position was replaced by a county executive, directly elected by popular vote, with expanded powers (e.g., veto). In 1993, the legislature enacted term limits for the executive office of 12 consecutive years to start in 1996. + Monroe county executives Name Title Party Term Clarence A. Smith county manager Republican January 1, 1936 – December 31, 1959 Gordon A. Howe county manager Republican January 1, 1960 – December 31, 1971 Lucien A. Morin county managercounty executive Republican January 18, 1972 – December 31, 1982January 1, 1983 – December 31, 1986 Thomas R. Frey county executive Democratic January 1, 1987 – December 31, 1991 Robert L. King county executive Republican January 1, 1992 – January 14, 1995 John D. "Jack" Doyle county executive Republican January 14, 1995 – December 31, 2003 Maggie Brooks county executive Republican January 1, 2004 – December 31, 2015 Cheryl L. Dinolfo county executive Republican January 1, 2016 – December 31, 2019 Adam J. Bello county executive Democratic January 1, 2020 –
Sheriff The Monroe County Sheriff's office (MCSO) provides law enforcement and has the constitutional authority to operate the county jail and provide civil functions. As with most counties in New York, the MCSO also performs a range of police services and provides physical and operational security to the courts. The MCSO is led by a sheriff who is elected by the residents of Monroe County, serving a 4-year term. The sheriff is considered the highest police official in the county, followed by an appointed undersheriff and subordinate chief deputy. The Monroe County Sheriff is Todd K. Baxter, a Democrat.
Organizationally, the office is composed of numerous bureaus, each responsible for a given scope of functional operations. The jail bureau is the largest component of the sheriff's office, overseeing an inmate population of around 1,000. Under the New York State Constitution, the sheriff is the warden of the county jail.
The police bureau of the sheriff's office operates a sizable road patrol force which serves municipalities within Monroe County that do not independently enforce traffic. They are also responsible for primary police patrols at the Greater Rochester International Airport and parks throughout the county. Deputies assigned to the marine unit patrol the coastline of Lake Ontario as well as Irondequoit Bay. The police bureau further employs a mounted unit, bomb squad, SWAT team, hostage recovery, criminal investigations, scuba, and canine units. The court security bureau provides security at the Hall of Justice as well as at the state appellate court building.
In 2011, the uniforms were named the 2011 Public Safety Uniform Award in the County Sheriff's/Police Department category by the North American Association of Uniform Manufacturers and Distributors (NAUMD).
Legislative branch The county's legislative branch consists of a 29-member county legislature which replaced the earlier 43-member board of supervisors on January 1, 1967. Members meet in the legislative chambers on the fourth floor of the county office building. All 29 members of the legislature are elected from districts. There are 16 Democrats and 13 Republicans. The president of the legislature is Yversha Román, a Democrat. In 1993, the legislature enacted term limits of 10 consecutive years to start in 1996. Legislators can return to the office after not being in the legislature for a term. Since the enacting of term limits, as of 2024 four legislators (Stephanie Aldersley, Karla Boyce, Calvin Lee Jr., and Robert Colby) returned after previously leaving due to the term limit; Boyce was reelected again three times; Lee and Colby were appointed to fill vacancies before subsequently being reelected themselves; and Aldersley was appointed before being defeated for reelection.