Leonia is a borough in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the borough's population was 9,304, an increase of 367 (+4.1%) from the 2010 census count of 8,937, which in turn reflected an increase of 23 (+0.3%) from the 8,914 counted in the 2000 census. The borough is a suburb of New York City located near the western approach to the George Washington Bridge.
Leonia was formed as the result of a referendum passed on December 5, 1894, from portions of Ridgefield Township. The borough was formed during the "boroughitis" phenomenon then sweeping through Bergen County, in which 26 boroughs were formed in the county in 1894 alone. Portions of Leonia were taken on February 19, 1895, to form the Township of Teaneck.
New Jersey Monthly magazine ranked Leonia as its 31st best place to live in its 2008 rankings of the "Best Places To Live" in New Jersey.
The original inhabitants of Leonia were the Hackensack tribe (Ashkineshacky) of Native Americans. The population was about 1,000 before the Europeans settled in the area. At the time of the American Revolutionary War, Leonia was known as part of the English Neighborhood, a name that survives in neighboring Englewood. It was settled in 1668 mainly by Dutch and English farmers, making it one of the oldest communities in the state and county. A third of the population was African slaves. It was located on the western slope of the Palisades, and started as a quiet farming community. Leonia's proximity to New York City and its major universities, theaters and performing venues contributed to Leonia's place in the world of art and academics, with many artists and leading thinkers finding a home there in the twentieth century.
The local economy that had been focused on agriculture underwent economic and cultural growth during the late nineteenth century, marked by the introduction of train service and was originally called West Fort Lee. J. Vreeland Moore and other town leaders chose the name "Leonia" in 1865 in honor of American Revolutionary War General Charles Lee, for whom Fort Lee was named.