When the Northwest Territory was organized in 1787,the area now known as Elkhart was mainly inhabited by the Ottawa, Chippewa, and Potawatomi Indian tribes. In 1829, the Village of Pulaski was established, consisting of a post office, mill, and a few houses on the north side of the St. Joseph River. Two years later, Dr. Havilah Beardsley moved westward from Ohio and purchased one square mile of land from Pierre Moran (a half French, half Native American Potawatomi Chief) in order to establish a rival town named Elkhart. In 1839, the Pulaski Post Office was officially changed to Elkhart.

Elkhart County was founded exclusively by immigrants from New England. These were old stock "Yankee" immigrants, that is to say they were descended from the English Puritans who settled New England in the 1600s. The completion of the Erie Canal caused a surge in New England immigration to what was then the Northwest Territory. The end of the Black Hawk War led to an additional surge of immigration, once again coming almost exclusively from the six New England states as a result of overpopulation combined with land shortages in that region. Some of these later settlers were from upstate New York and had parents who had moved to that region from New England shortly after the Revolutionary War. New Englanders and New England transplants from upstate New York were the vast majority of Elkhart County's inhabitants during the first several decades of its history. These settlers were primarily members of the Congregational Church though due to the Second Great Awakening many of them had converted to Methodism and some had become Baptists before coming to what is now Elkhart County. The Congregational Church subsequently has gone through many divisions and some factions, including those in Elkhart County are now known as the Church of Christ and the United Church of Christ. As a result of this heritage the vast majority of inhabitants in Elkhart County, much like antebellum New England were overwhelmingly in favor of the abolitionist movement during the decades leading up to the Civil War. Correspondingly, many inhabitants of Elkhart County fought in the Union Army during the Civil War. In the late 1880s and early 1890s Irish and German migrants began moving into Elkhart County, most of these later immigrants did not move directly from Ireland and Germany, but rather from other areas in the Midwest where they had already been living, particularly the state of Ohio.

By the late 19th century and early 20th century, musical instrument factories, Miles Medical Company, and numerous mills set up shop and became the base of the economy. In 1934, the first recreational vehicle factory opened in Elkhart. Similar companies followed suit for the remainder of the decade, and the economy continued to grow until the rationing of materials in World War II. After the war, growth picked back up and, by 1949, Elkhart was officially dubbed the "RV Capital of the World."

In 1851, the Michigan Southern & Northern Indiana Railroad Company built the first rail line through the city, and by 1852 the first passenger train passed through town. This, in turn, caused major population growth. Today, Norfolk Southern has the biggest railroad presence in town, although Elkhart has two other railroads: Shortline-Elkhart and Western (operated by Pioneer Railcorp) and Regional-Grand Elk (operated by Watco). Amtrak has two trains that stop in Elkhart, Lake Shore Limited and Capitol Limited, both of which stop at the Elkhart station. Canadian Pacific runs 6-8 trains through town on Norfolk Southern's trackage.

In 1867, Elkhart Hydraulic Company built the first hydroelectric dam across the St. Joseph River and by 1870, it powered the city. Today, the dam still produces electric power and is operated by Indiana Michigan Power, a subsidiary of American Electric Power.

In 1889, the second electric streetcar system in the world began operation on the city's streets. It has since been decommissioned.

The Beardsley Avenue Historic District, Albert R. Beardsley House, Dr. Havilah Beardsley House, Emmanuel C. Bickel House, Bridge Street Bridge, Charles Gerard Conn Mansion, Elkhart Downtown Commercial Historic District, Green Block, William and Helen Koerting House, Lerner Theatre, Mark L. and Harriet E. Monteith House, Morehous Residential Historic District, State Street-Division Street Historic District, and Young Women's Christian Association are listed on the National Register of Historic Places.

Although apparently a name of German or Germanic origin, the etymology of the city's name is disputed. One source argues that the city's Island Park looks like an elk's heart. Another source claims that the origin of the city's name was the Shawnee Indian Chief Elkhart (Mihsheweteha : Elk-heart), cousin of the famous Chief Tecumseh, and the father of Mishawaka (Mihshewehkwewa : Elk-woman), the namesake of neighboring Mishawaka. Other sources state that the name stems from the Miami-Illinois village name Mihšiiwiateehi (Elk Hart).

As of the census of 2010, there were 50,949 people, 19,261 households, and 11,942 families residing in the city. The population density was 2,172.7 inhabitants per square mile (838.9/km²). There were 22,699 housing units at an average density of 968.0 per square mile (373.7/km²). The racial makeup of the city was 66.1% White, 15.4% African American, 0.6% Native American, 0.9% Asian, 0.1% Pacific Islander, 12.9% from other races, and 4.1% from two or more races. Hispanic or Latino of any race were 22.5% of the population.

There were 19,261 households, of which 36.9% had children under the age of 18 living with them, 36.7% were married couples living together, 18.5% had a female householder with no husband present, 6.7% had a male householder with no wife present, and 38.0% were non-families. 30.8% of all households were made up of individuals, and 10.5% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.25.

The median age in the city was 32.7 years. 29.1% of residents were under the age of 18; 9.4% were between the ages of 18 and 24; 27.5% were from 25 to 44; 22.5% were from 45 to 64; and 11.5% were 65 years of age or older. The gender makeup of the city was 48.2% male and 51.8% female.

As of the 2000 census, there were 51,874 people, 20,072 households, and 12,506 families residing in the city. The population density was 2,428.0 people per square mile (937.7/km²). There were 21,688 housing units at an average density of 1,015.1 per square mile (392.0/km²). The racial makeup of the city was 71.5% White (predominantly German American), 14.7% African American, 0.4% Native American, 1.2% Asian, 0.1% Pacific Islander, 9.2% from other races, and 2.9% from two or more races. Hispanic or Latino of any race were 14.8% of the population.

Of the 20,072 households, 62.3% were occupied by families, 33.4% had children under the age of 18 living with them, 40.9% were married couples living together, 15.3% had a female householder with no husband present and 37.7% were non-families. 30.3% of all households were made up of individuals, and 10.3% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.16.

In the city, the population was spread out, with 28.4% under the age of 18, 11.1% from 18 to 24, 31.7% from 25 to 44, 18.0% from 45 to 64, and 10.7% who were 65 years of age or older. The median age was 31 years. For every 100 females, there were 96.9 males. For every 100 females age 18 and over, there were 94.6 males.

The median income for a household in the city was $34,863, and the median income for a family was $40,514. Males had a median income of $30,674 versus $22,760 for females. The per capita income for the city was $17,890. About 11.1% of families and 13.6% of the population were below the poverty line, including 18.6% of those under age 18 and 9.0% of those age 65 or over.