The Rock Island also built a depot - complete with an electric car to ride around Midlothian - and traffic to Midlothian began increasing. By 1915, land developers who saw opportunity in Midlothian began arriving, purchased land from farmers and subdivided the farms into tracts of land for housing developments. Soon the first general store opened, then a school, and then more businesses offering goods and services to serve the community's fast-growing population. The Midlothian Fire Department was organized in 1924.
By 1927, there were so many people living in the area that community leaders decided it was time to formally organize the community and incorporate it. On March 17, it was incorporated as the Village of Midlothian, taking its name from the golf course around which the community had grown and prospered. The following month, John H. Hamilton was elected as the Villages' first president.
In the '30s and '40s, homes continued to be built for people moving to and settling down in Midlothian. The Kreis Brothers opened the Ford Garage (where the village's fire engine was kept) and Chuck Cavallini began selling ice cream from his corner "Sweet Shop" (the Cavallini family would later own and operate the renowned Cavallini's Restaurant - home of the "Chuck Wagon" dinners - which served patrons from Midlothian, surrounding communities and even Chicago for a half century before closing in 1989). The first copy of The Messenger newspaper was printed in 1929 by the Andrews brothers, above the old Largent store located on 147th Street just west of Kildare. The first editor was Kevin McGann, who later served as aide-de-camp to General Dwight Eisenhower during World War II. McGann also worked with the General on his two books.
In 1949 Midlothian's present Village Hall was built at 148th and Pulaski. It provided a permanent "home" for the village staff. The facilities have been expanded and recently renovated; the Village Hall complex now houses the administrative staff, public works offices and garages, the fire department administrative offices and Station 1, the police department administrative offices, records, communications and investigative resources, a conference room and meeting room used by residents as well as staff, and the Village Board Chambers. Monthly hearings for parking tickets and housing-code violations are also held in the Chambers.
There were 5,158 households out of which 37.1% had children under the age of 18 living with them, 53.9% were married couples living together, 13.7% had a female householder with no husband present, and 27.4% were non-families. 22.7% of all households were made up of individuals and 8.0% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.26.
In the village the population was spread out with 28.1% under the age of 18, 8.6% from 18 to 24, 32.0% from 25 to 44, 21.3% from 45 to 64, and 10.0% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 95.0 males. For every 100 females age 18 and over, there were 91.8 males.
The median income for a household in the village was $50,000, and the median income for a family was $58,945. Males had a median income of $43,693 versus $31,116 for females. The per capita income for the village was $20,150. About 5.5% of families and 7.0% of the population were below the poverty line, including 7.3% of those under age 18 and 9.4% of those age 65 or over.
David Dowaliby, who was accused of murdering his adopted daughter, Jaclyn Dowaliby, lived in Midlothian.