Ennis is on the Southern Pacific Railroad and at the intersection of Interstate Highway 45, State highways 34, 75, and 287, and Farm roads 85, 879, 1183, 1722, and 3413, fourteen miles southeast of Waxahachie in southeastern Ellis County. Bardwell Lake, a popular recreational area, is less than a mile south of the city limits. The Houston and Texas Central Railway reached the area in 1871, and the community established there was named for an early railroad official, Col. Cornelius Ennis. The David Rose survey of 300 acres and the W. H. Bundy survey of 347 acres were purchased by the trustees of a land company in 1872. Capt. W. G. Veale selected the townsite in May, and Theo Kosse mapped it in August and laid out the streets and alleys. The first train ran through the community that year, on its way from Corsicana to Dallas. Citizens of Burnham, a small town to the south, responded violently to being bypassed and attacked the new community, killing one man and wounding several.
The Ennis post office opened in 1872 with J. M. Dickson as the postmaster and railroad agent. The first church in Ennis was the Cumberland Presbyterian Church, originally founded in Burnham, which moved to Ennis in 1872. As an incentive to settlement, the railroad offered free town lots to any Christian communion that would build a church. Ennis incorporated in November 1873 and held its first election in April 1874; Charles Pannil was elected the first mayor. The Evening Argus was founded in 1873, and the Temperance Council was established to provide an alternative to "drunken carousing." By 1874 the community had a population of 300 and rising land values. Ennis reached 3,000 by 1890, when it had two banks, a cotton compress, three cottonseed depositories, a cotton gin, a fruit-canning business, a brickyard, an opera house, and two weekly newspapers, the Local and the Saturday Review.
The Houston and Texas Central chose Ennis as its northern division headquarters in an agreement requiring that Ennis provide water for the railroad. The machine shops and roundhouse employed several hundred men. One condition of the agreement was that as long as Ennis was able to furnish water the shops could not be moved from the community. In 1891 the city of Ennis built the first of three lakes for this purpose, followed by another in 1895, and the last in 1940. This water was also used by the city for uses besides drinking, while wells were used for drinking water. Between 1910 and 1915 the railroad tried to move the shops, but the community was supported in the courts, and the shops remained in Ennis. In 1894 Ennis received its second railroad, the Texas Midland, which provided service from Paris, Texas, by 1897.
By 1914 Ennis had a population of 6,600, eleven churches, four banks, four cotton gins, a cottonseed oil mill and cotton compress, a mattress factory, an ice factory, a light and power plant, and two newspapers, the Ennis Daily News and the Weekly Local. In 1930 the community had a population of 7,069 and 205 businesses, including two ice companies, two printing companies, a cottonseed oil company, and a creamery. Ennis remained a predominantly agricultural community, as demonstrated in the chamber of commerce's slogan, "Where Railroads and Cotton Fields Meet." In 1934 the Texas and New Orleans Railroad acquired both the Texas Midland and the Houston and Texas Central. In 1942 the tracks between Ennis and Kaufman, which had been the Texas Midland, were abandoned because of frequent washouts in the Trinity River bottoms. From then on Ennis had only one railroad. In 1961 the Southern Pacific acquired the Texas and New Orleans.
In 1956 Ennis changed to a city manager government. New elections were held in 1957, and a comprehensive zoning ordinance was implemented in 1959. In 1964 a new hospital was built. Lake Bardwell was completed in 1965 and was used for flood control, storage, and recreation. In 1968 the Ennis Municipal Airport, the only airport in the county, was completed. By 1970 Ennis had a population of 11,550 and 250 businesses. The city had become an industrial community, where items including business forms, trophies, furniture, clothing, printing, novelties, and concrete were manufactured. Although agriculture had become less important, cotton was still grown, and cattle raising had become more prevalent.
By the 1990s Ennis was part of the Dallas-Fort Worth metropolitan area. In 1990 it had a population of 13,883 and fifty-three manufacturers. The community published three newspapers: the Ellis County News, founded in 1988 by a merger of the Weekly Local and the Palmer Rustler, both founded in 1891; the Press, founded in 1974; and the Ennis Daily News, founded in 1891. The Texas Motorplex, a professional and amateur racetrack founded in 1986, seated 26,000 and held races throughout the year. Two popular annual events are held in Ennis, the Bluebonnet Trails, begun in the 1930s and held in late April and early May when the bluebonnets are in bloom, and the Ennis Polka Festival, founded in 1967 and held every May, which brings thousands of visitors to the community to celebrate its Czech heritage. In 2000 the population had grown to 16,045.