I think that argument can be made with regards to Aspergers. People who used to be written off as "quirky" are now given the label of Aspergers. It is a case of more diagnosis, not more cases. I am not so sure that is the case with more classical or moderate-severe autism - whose rates are increasing as well. Classical autism would have been diagnosed in any era.
As far as the US goes (I have no idea about Canada or other countries) the rate of 1 in 88 is for ASD (autism spectrum disorder) which includes PDD-NOS (pervasive developmental disorder not otherwise specified; it's been referred to as "sub-threshold" autism), Asperger's Syndrome, and Autistic Disorder, so I haven't seen a rate of each disorder. Autistic Disorder and PDD-NOS were added to the DSM in 1987 (AD was Infantile Autism added in 1980). Asperger's Syndrome was added in 1994. Criteria for Autism Disorder was expanded in 1994. The IDEA was signed into law in 1990 and was amended in 2004 to further improve services for children with disabilities. Some of the data used to determine the CDC rate was based on was educational diagnoses which wouldn't have happened all that long ago. Then there is the advocacy groups and the internet increasing awareness of the issue and the services available through early intervention and the schools.
Now, I'm not ruling out the fact that the incidence of ASD could actually be on the rise, but I think expansion of the diagnosis, increased awareness, improved educational services and early intervention, and various other changes explain a big chunk of the increase in the rate of autism in US. In other words. I just don't think there is an "epidemic" as it's often referred to although I wouldn't rule out an increase. I'm tempted to offer some anecdotal evidence, but I'll stop.
I'm about the same age, and I knew a little boy when I was a kid who had autism. His mom was friends with my mom. I still remember my mother trying to explain to me what being autistic meant and she was fumbling for words and saying it was something like being "retarded" but "different." I've read a few places that people with autism were often diagnosed with other issues like mental retardation.
I also remember that the kids in special education were kept very separate from the rest of the kids at school as I think was pretty standard back then. Also, it was more common for children with disabilities not be in regular schools. So considering all that, it's no wonder I didn't know or see more. Also, looking back, I do wonder if a few kids that had behavior issues or were quirky would be diagnosed with ASD if they were in school today.
Edited by AbbyGrant - 4/23/12 at 3:48pm