Mullingar was established in 1909 by Charles and Mark Comerford and their families.

They left Eldorado, Ontario, and homesteaded in the Mullingar district in 1906.

In 1907, a country post office was erected[2] and the name "Mullingar" was chosen by Mark Comerford; to choose he closed his eyes and pointed to a map of Ireland.

He was also one of the five township organizers to pave the way for its local improvement district, and was Reeve for the RM #466 for 19 years.

Although the original post office is not there, the postal code and boxes are still used.