Disability as a Social Construction

The attitude towards people with a disability is something that has changed over time. In many cases throughout history i feel as though people with disabilities were considered liabilities, often not worth being taken care of. In other cases disability has been put up on stage as something worth gawking at. In the early 20th century "freak shows" which displayed disabled persons were common at carnivals and the circus. With that in mind, do you feel that disability is, like we know race to be, a social construction? If so, where is this social construction of disability being used to discriminate against disabled persons?