Each state has an Office of Rehabilitation Services. In many states it starts with the name of the state and Rehabilitation Services. For example: YOUR STATE Rehabilitation Services or even Y.S.R.S. When parents are able to find this office and help their teenager get connected with it, they are able to start the process of qualifying for services.
Unlike with the school system, the teenager or young adult with Autism has to qualify and advocate with this office for services. There are typically a variety of possible services. Some of these may be testing for interest and skill areas, a variety of types of assistance to go to college or trade school, job developing, job coaching, job aides, following along, etc.
These services are a good place to start when looking at employment. Sometimes people with Autism who are more involved will need more services than the Rehabilitative Office can supply over the long haul but it is still a good start. Typically the Rehabilitative Office is also able to send you in the direction of longer employment supports.
At 18 year of age a person with Autism is considered a Competent Major and is responsible for making decisions for them selves. Unless you have used the legal system to continue to make decisions when your child is an adult, this agency will deal primarily with your child. Of course your child can choose to have you along for most of the process as support.
Employment on some level is possible for people with disabilities including Autism. Using the office of Rehabilitation Services gives your child access to a variety of tools designed to meet their needs. Testing can show the areas you child already has skills in. Various job related tools can help finding that first job.
Supports in college can include help advocating for a reduced course load while keeping financial assistance. It could be help scheduling classes in such a way to reduce the stress of classes requiring more effort. The Rehabilitation counselor can help your child find the Office of Disability on the campus and negotiate for accommodations in class as well.