Essex County is located in the northeastern part of the U.S. state of New Jersey, and is one of the centrally located counties in the New York metropolitan area. As of the 2020 census, the county was the state's second-most populous county,Table1. New Jersey Counties and Most Populous Cities and Townships: 2020 and 2010 Censuses, New Jersey Department of Labor and Workforce Development. Accessed December 1, 2022. with a population of 863,728, its highest decennial count since the 1970 census and an increase of 79,759 (+10.2%) from the 2010 census count of 783,969.Wu, Sen-Yuan. NJ Labor Market Views; Population Keeps Growing in the Most Densely Populated State, United States Census Bureau, March 15, 2011. Accessed December 26, 2022. The county is part of the North Jersey region of the state.Willis, David P. "'This is how wars start': Does Central Jersey include both Ocean and Union counties?", Asbury Park Press, February 20, 2023. Accessed March 31, 2024. "North Jersey is defined as Sussex, Warren, Morris, Passaic, Bergen, Essex and Hudson counties; South Jersey would be Burlington, Camden, Gloucester, Atlantic, Salem, Cumberland and Cape May counties. But for Central, things get a little tricky. It would include Hunterdon, Somerset, Union, Middlesex, Mercer, Monmouth, and Ocean counties."

The United States Census Bureau's Population Estimates Program estimated a 2025 population of 896,379, an increase of 32,651 (+3.8%) from the 2020 decennial census. Its county seat is Newark,New Jersey County Map, New Jersey Department of State. Accessed December 22, 2022. the state's most populous city with a 2020 census population of 311,549.

In 2015, the county had a per capita personal income of $60,030, the eighth-highest in New Jersey and 153rd highest of 3,113 counties in the U.S.250 Highest Per Capita Personal Incomes available for 3113 counties in the United States: 2015, New Jersey Department of Labor and Workforce Development. Accessed October 24, 2017.Local Area Personal Income: 2015 , Bureau of Economic Analysis. Accessed October 24, 2017. The Bureau of Economic Analysis ranked the county as having the 94th-highest per capita income of all 3,113 counties in the U.S. and seventh-highest in New Jersey in 2009., Bureau of Economic Analysis, backed uo by the Internet Archive as of July 22, 2011. Accessed September 9, 2012.

History

Etymology The county is named after Essex, a county in the East of England.Kane, Joseph Nathan; and Aiken, Charles Curry. The American Counties: Origins of County Names, Dates of Creation, and Population Data, 1950–2000, p. 95. Scarecrow Press, 2005. . Accessed January 21, 2013.

History Essex was originally formed as one of four administrative districts within Province of East Jersey in 1675, together with Bergen, Middlesex and Monmouth districts. Essex County was formed within East Jersey on March 7, 1683.Snyder, John P. The Story of New Jersey's Civil Boundaries: 1606–1968, Bureau of Geology and Topography; Trenton, New Jersey; 1969. p. 125. Accessed June 6, 2012. The county was named after the English county of Essex. When the provinces of East Jersey and West Jersey were combined in 1702, the county boundaries were retained. Portions of Essex were taken in 1741 and transferred to Somerset County. In 1837, Passaic County was formed from portions of Essex and Bergen counties. In 1857, Union County was created from parts of Essex County.

Secession The municipalities of western Essex County have discussed secession from the county, to create a new county or be annexed to Morris County, spurred mainly by a belief that tax policy benefits the poorer, urban, eastern portions of the county at the expense of the wealthier, more suburban municipalities in the west of the county. From 2001 to 2003, Millburn, Montclair and Roseland all held nonbinding ballot referendums on the issue. Then-Montclair mayor Robert J. Russo gave a statement in 2003 about secession, "I've watched Essex County burden our people, with very little to show for it. We're fiscally conservative here and socially progressive – and we're finally rebelling."Pearce, Jeremy. "In Essex County, Secession Gathers Momentum", The New York Times, September 7, 2003. Accessed September 23, 2016. "Montclair and Roseland both have decided to test the winds for revolution. In November, each community plans to put the secession issue before the public, in the form of a nonbinding referendum. Two years ago, Millburn posed a similar question and was bowled over at the response: 88 percent of voters agreed that the town should take steps toward leaving Essex for neighboring Morris County."

Geography According to the U.S. Census Bureau, as of the 2020 Census, the county had a total area of , of which was land (97.4%) and was water (2.6%).2020 Census Gazetteer File for Counties in New Jersey, United States Census Bureau. Accessed April 1, 2023.

The county rises from generally flat in the east to the twin ridges of the Watchung Mountains in the western half, beyond which the land lowers again into the Passaic River valley.

The highest elevation is found at four areas scattered between Verona, North Caldwell, and Cedar Grove, reaching above sea level.New Jersey County High Points, Peakbagger.com. Accessed October 4, 2013. The lowest point is sea level, at Newark Bay.

Climate All of Essex County has a humid subtropical climate (Cfa) if the -3 °C isotherm is used. If the 0 °C isotherm is used, Cfa only exists in eastern Newark and the rest of the county has a hot-summer humid continental climate (Dfa). However temperatures do vary in various locations. In Newark, Eastern Essex County, and Southern/Southeastern Essex County, temperatures are relatively cool to hot, even in the winter months. Western Essex County has similar temperatures to Eastern Essex, but the elevation increase within the Watchung Mountains allows for some minor differences. An example would be that in January on Interstate 280 it could be raining in East Orange. Heading west on 280 there is a large hill that elevates from , a difference. At the top of the hill it could be snowing because of the 3 to 4 degree temperature differences.

In recent years, average temperatures in the county seat of Newark have ranged from a low of in January to a high of in July, although a record low of was recorded in February 1934 and a record high of was recorded on July 22, 2011, which is the highest temperature ever recorded in the state.Strunsky, Steve. "N.J. city set two heat records Sunday, one for hitting 100 degrees for a 5th straight day", NJ Advance Media for NJ.com, February 16, 2023. Accessed December 31, 2023. "It was in Newark — on July 22, 2011 — that the National Weather Service recorded New Jersey’s highest temperature on record, for any date, in any location, at 108 degrees, said Amanda Lee, a meteorologist at the National Weather Service’s Mount Holly forecast office." Average monthly precipitation ranged from in February to in July. In Roseland, average monthly temperatures range from in January to in July.Time Series Values for Individual Locations, Oregon State University. Accessed June 24, 2023.

Demographics Based on data from the 2010 census, Essex County is the 14th-most densely populated county in the United States, and was ranked New Jersey's second-most densely populated after Hudson County, which ranked sixth most-densely populated in the nation at 13,731.4 per square mile as of 2010.Staff. "Census 2010 data show population and diversity trends" , USA Today. Accessed October 4, 2013. Click on "Population per Square Mile" to sort counties nationwide by descending population density." Newark, with a population density of 11,458.3 people per square mile, is the largest municipality in the county both in terms of land area (24.19 square miles) and population (277,140), while Caldwell is the smallest in terms of land area (1.17 square miles) and Essex Fells has the smallest population (2,113)., United States Census Bureau. Accessed June 6, 2012. Many of the county's smallest municipalities have population densities that are comparable to those of many big cities, and are well above the state's average which in turn is the highest in the nation.

Like many of the counties of Northern New Jersey near New York City, which tend to have sharp divides between relatively rich suburban neighborhoods and less wealthy, more densely populated cities nearby, the eastern region of Essex County tends to be poorer and more urbanized, while the western parts tend to be more affluent and suburban. The wide area of Eastern Essex has significant pockets of high population, high building density, high poverty, and high crime rates. Within this general area, however, are numerous areas composed of safe, mixed and middle-income neighborhoods of diverse populations. For example, north and west sides of Newark have well-kept suburban areas such as Vailsburg and Forest Hill. The east side of Newark is the Ironbound, a working-class Brazilian and Portuguese community. East Orange is home to the Presidential Estate neighborhood, a well-kept area of large, pre-war, single-family homes. Belleville and Bloomfield are suburbs with historic Italian communities that, in spite of retaining a core Italian-American population, now have many immigrants from Latin America and Asia. As of the 2000 Census, 36% of Nutley residents indicated that they were of Italian ancestry, the 12th-highest of any municipality in the nation and third-highest in New Jersey.Italian Communities , EPodunk. Accessed October 4, 2013.

Beginning at about the turn of the 20th century, Essex County led the state in the rebuilding and rehab of its housing stock. In the 2000s, Newark led the state in the issuance of building permits. Many reasons were cited: citywide incentives to encourage construction development, an improving local economy, the rising demand of low-cost housing so close to Manhattan. Newark has since then become one of the fastest-growing cities in the entire Northeast,Roberts, Sam. "Biggest Urban Growth Is in South and West", June 28, 2007. Accessed November 13, 2007., accessed November 14, 2006 and reported a gain in median income and drop in poverty rate. This is a turnaround from the deterioration and abandonment experienced in the post-riot 1970s, 1980s and early part of the 1990s.