The population of Melvin City is spread out, with 38.1% of the total population under the age of 18 living in the city. A large majority of residents (72%) were married, while 15.7% were non-families. The median age was 39, and there were more males than females living in the city. The median household size was 2.88, while the median family size was 3.23.
The median income for residents in Melvin is $47188. The city has three hundred and eleven voters of voting age. The majority of residents are white, while 11.5% of the population is of Asian or other ethnic group. Only 6.6% of Melvin residents are Hispanic. The unemployment rate in Melvin is 3.5% among those aged 16 and older. One-third of residents in Melvin, Illinois are employed by the local, state, and federal governments.