New Castle is a city in Henry County, Indiana, 44 miles (71 km) east-northeast of Indianapolis, on the Big Blue River. In 1900, 3,406 people lived in the town; in 1910, 9,446; in 1920, 14,458; and in 1940, 16,620. The population was 18,114 at the 2010 census. The city is the county seat of Henry County. New Castle is home to New Castle Fieldhouse, the largest high school gymnasium in the world. The city is surrounded by a farming district. In the past, it was an industrial centre of some importance, where the leading manufactures included sheet iron and steel, automobiles, caskets, clothing, scales, bridges, pianos, furniture, handles, shovels, lathes, bricks, flour, etc.
New Castle Correctional Facility, with a capacity of over 2,000 inmates, is located just north of the city.
New Castle is located at .
According to the 2010 census, the city has a total area of 7.32 square miles (19.0 km2), of which 7.30 square miles (18.9 km2) (or 99.73%) is land and 0.02 square miles (0.052 km2) (or 0.27%) is water.
New Castle is a third class city and has a seven member city council chaired by the mayor. One council member is elected from each of the city's five districts and two are elected at-large. The clerk-treasurer and city judge are also elected offices. City elections are held every four years in the year preceding presidential elections.
The mayor is elected by popular vote and appoints the police chief, fire chief, city attorney, and department heads of the various municipal agencies.
|Source: US Census Bureau|
As of the census of 2010, there were 18,114 people, 7,769 households, and 4,660 families residing in the city. The population density was 2,481.4 inhabitants per square mile (958.1 /km2). There were 9,002 housing units at an average density of 1,233.2 per square mile (476.1 /km2). The racial makeup of the city was 95.1% White, 1.9% African American, 0.2% Native American, 0.4% Asian, 0.6% from other races, and 1.8% from two or more races. Hispanic or Latino of any race were 1.7% of the population.
There were 7,769 households out of which 30.1% had children under the age of 18 living with them, 39.0% were married couples living together, 16.1% had a female householder with no husband present, 4.9% had a male householder with no wife present, and 40.0% were non-families. 34.9% of all households were made up of individuals and 15.8% had someone living alone who was 65 years of age or older. The average household size was 2.29 and the average family size was 2.93.
The median age in the city was 39.5 years. 23.4% of residents were under the age of 18; 8.8% were between the ages of 18 and 24; 24.7% were from 25 to 44; 26.4% were from 45 to 64; and 16.7% were 65 years of age or older. The gender makeup of the city was 46.7% male and 53.3% female.
As of the census of 2000, there were 17,780 people, 7,462 households, and 4,805 families residing in the city. The population density was 2,987.5 people per square mile (1,153.8/km²). There were 8,042 housing units at an average density of 1,351.3 per square mile (521.9/km²). The racial makeup of the city was 96.37% White, 1.85% African American, 0.22% Native American, 0.21% Asian, 0.02% Pacific Islander, 0.41% from other races, and 0.91% from two or more races. Hispanic or Latino of any race were 1.09% of the population.
There were 7,462 households out of which 28.9% had children under the age of 18 living with them, 46.7% were married couples living together, 13.8% had a female householder with no husband present, and 35.6% were non-families. Some 31.5% of all households were made up of individuals and 15.3% had someone living alone who was 65 years of age or older. The average household size was 2.32 and the average family size was 2.90.
In the city the population was spread out with 23.5% under the age of 18, 8.6% from 18 to 24, 28.9% from 25 to 44, 21.8% from 45 to 64, and 17.3% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 88.7 males. For every 100 females age 18 and over, there were 84.3 males.
The median income for a household in the city was $30,688, and the median income for a family was $37,463. Males had a median income of $32,624 versus $20,554 for females. The per capita income for the city was $17,587. About 10.6% of families and 12.4% of the population were below the poverty line, including 15.7% of those under age 18 and 9.2% of those age 65 or over.
- Nine of the eleven largest high school gyms in the United States are in Indiana. The largest of these is the New Castle Fieldhouse at Chrysler High School. The fieldhouse has a capacity of 9,325.The fieldhouse is notable for a 1961 State Sectional Game between New Castle and Lewisville (now part of South Henry School Corporation) in which the fans attending the game were snowed in.The next morning food was delivered to the Fieldhouse by a local bakery and a church service was piped into the gym. The gym has also played host to the 2006 Indiana Class 3A Basketball Champs and the 2007 Class 4A Volleyball Champions 
- New Castle is home to the Indiana Basketball Hall of Fame located near New Castle Chrysler High School.
- Next to New Castle Chrysler High School is a Native American mound dated to approximately 2000 BP. This mound contains depressions which align to sunrise/sunset during the equinoxes as well as aligning with depressions in similar mounds tens of miles away.
- Steve Alford, basketball player
- Kent Benson, basketball player
- Omar Bundy; military hero Indian Wars, Spanish-American War, General World War I
- Trevor Chowning, pop artist and former Hollywood talent agent/producer
- Richard Crane-American actor
- William Grose, American Civil War General
- Bruce Harris, basketball player, Vietnam War General
- Vern Huffman, All-American basketball and football player for Indiana University
- Robert Indiana, artist who created the world renowned Love sculpture
- David Lee Roth, rock musician with Van Halen
- Wilbur Wright, inventor
- Dakoda Armstrong, Driver of the #98 EverFi Toyota for ThorSport Racing in the NASCAR Camping World Truck Series.
- "US Gazetteer files 2010". United States Census Bureau. Retrieved 2012-12-11.
- "American FactFinder". United States Census Bureau. Retrieved 2012-12-11.
- "Population Estimates". United States Census Bureau. Retrieved 2013-01-02.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "US Board on Geographic Names". United States Geological Survey. 2007-10-25. Retrieved 2008-01-31.
- "Find a County". National Association of Counties. Retrieved 2011-06-07.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.
- "2010 Census U.S. Gazetteer Files for Places – Indiana". United States Census. Retrieved 2012-04-21.
- News article, paragraph three, from USA Today, February 25, 2004.