Ontario's last three institutions for adults with a developmental disability were:

Huronia Regional Centre in Orillia

• When it opened: 1876
• Originally called the Orillia Asylum for Idiots. It was renamed the Ontario Hospital School.
• Resident population in 1971: 1,875
• When it closed: 2009

Rideau Regional Centre in Smiths Falls

• When it opened: 1951
• Originally named the Ontario Hospital School, Smiths Falls
• Resident population in 1971: 2,070
• When it closed: 2009

Southwestern Regional Centre in Chatham-Kent

• When it opened: 1961
• Originally named the Ontario Hospital School for Retarded Children at Cedar Springs
• Resident population in 1971: 937
• When it closed: 2008