Swinford Union was established on April 2nd, 1840 and had a Board of Guardians numbering 28 members. A six-acre site was acquired from Sir William Brabazon by the assistant commissioner Joseph Bourke for the erection of a workhouse.

The contract was signed on the October 16th, 1840 and the building was completed in February 1842.

It was in use up to 1926.

It could accommodate 420 adults and 280 children. Collecting the rates proved to be difficult and this delayed's opening.

It was officially opened on 26th March 1846, and the first inmates were admitted on 14th April 1846.

By the end of 1846, there was overcrowding in the workhouse with as many as 200 people per day seeking admission.

At the height of the Great Famine in 1847 hundreds of people flocked there for relief and shelter. During these years disease was rampant, people were dying so fast from starvation and fever, that the grave was left open to receive corpses.

Conditions inside the workhouse were inhuman and degrading, discipline was strict, and inmates were compelled to work without compensation.

In 1847 the Soup Kitchen Act was set up to try to relief the paupers. Sir William Brabazon bought two houses for the establishment of soup kitchens. In the same year, fever sheds and temporary wards were erected giving accommodation for an extra 260 people. G. Wilkinson designed the fever hospital.

In 1926 the workhouse closed down, and the remaining inmates were transferred to Castlebar where Sr. M. Berchmans took charge of them in The County Home.

In the 1930s parts of the workhouse and infirmary were demolished. Only the fever hospital, which was formerly the administration building of the Union, is still in existence and retains its original features.

The Swinford Workhouse Mass Grave, located near the present day District Hospital, is very well preserved. It was restored in the 1960s. The people of Swinford erected a to the memory of the 564 victims of the Great Famine buried here.