Parsippany-Troy Hills was incorporated as a township by an Act of the New Jersey Legislature on March 12, 1928, from portions of Hanover Township, based on the results of a referendum held on May 9, 1928.
In 2006, Parsippany-Troy Hills was recognized by Money magazine as the 17th-ranked of the Best Places to Live in the United States, the highest-ranked location in New Jersey. In 2008, it moved up to 13th position. The township was not on the 2007 list because that year's list included only municipalities with a population of 50,000 or less.
As of the census of 2000, there were 50,649 people, 19,624 households, and 13,167 families residing in the township. The population density was 2,115.5 people per square mile (816.9/km²). There were 20,066 housing units at an average density of 838.1/sq mi (323.6/km²). The racial makeup of the township was 74.28% White, 3.11% African American, 0.12% Native American, 18.06% Asian, 0.06% Pacific Islander, 1.90% from other races, and 2.48% from two or more races. Hispanic or Latino of any race were 6.98% of the population.
There were 19,624 households out of which 29.5% had children under the age of 18 living with them, 56.2% were married couples living together, 7.6% had a female householder with no husband present, and 32.9% were non-families. 27.1% of all households were made up of individuals and 6.7% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.13.
In the township the population was spread out with 21.0% under the age of 18, 6.7% from 18 to 24, 35.2% from 25 to 44, 25.9% from 45 to 64, and 11.2% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 97.8 males. For every 100 females age 18 and over, there were 94.7 males.
The median income for a household in the township was $68,133, and the median income for a family was $81,041 (these figures had risen to $83,227 and $102,714 respectively as of a 2007 estimate). Males had a median income of $51,175 versus $38,641 for females. The per capita income for the township was $32,220. About 2.6% of families and 3.9% of the population were below the poverty line, including 4.0% of those under age 18 and 6.3% of those age 65 or over.
Parsippany-Troy Hills has a large Indian American community, mainly middle and upper class. As of the 2000 census, 8.39% of Parsippany-Troy Hills' residents identified themselves as being of Indian American ancestry, which was the eighth highest of any municipality in New Jersey, for all places with 1,000 or more residents identifying their ancestry. The community also has an equally large Chinese-Taiwanese American population.
Parsippany lies at the crossroads of many major roadways including Interstates 80, 280 and 287, U.S. Routes 46 and 202, New Jersey Routes 10 and 53, as well as County Route 511.
The Mount Tabor station offers train service on the New Jersey Transit Morristown Line, with service to and from Penn Station in Midtown Manhattan and Hoboken Terminal.
China Airlines provides private bus service to John F. Kennedy International Airport from the Top Quality Food Market 828 Route 46 in Parsippany to feed its flight to Taipei, Taiwan.