When I was a kid kids with autism were very rare. Today almost 20% of kids are somewhere on the Asperger's spectrum. This is an horrific growth in an affliction that deprive tens of millions of people of their full potential to live their best life. The fact that it's increased exponentially over recent decades shows that it's caused by some environmental factor that is exponentially increasing. No pathogen, genetic trait, or similar, more traditional vector can be the cause. Something that's increasing in frequency as autism is must be what is causing autism.
In Mccullough Foundation Report - Determinants of Autism Specturm Disorder many different possible causes are compared, and for the first time vaccines have been included in the potential causes. The Supplemental material (data, charts, images, and etc) is also available for free download in PDF format.
Nic Hulscher, an epidemiologist who has lately become widely known for his ability to say it like it is without protecting funding sources, sponsors, or simply parroting propaganda, points out that this is the first time vaccines have actually been compared to other potential causes of autism. That fact alone should alert you to what the most likely causes of autism are, and enable you to understand why preachers of the faith in vaccines make statements like 'We don't know what causes autism, but it's not vaccines.'
Folks that have kids, or paid attention to the discussion of vaccine safety in recent years will not be surprised to know that the kid with their hand in the cookie jar is shown to be strongly associated with cookies missing from the jar. The strongest deternminant of autism is vaccination.
"Combination and early-timed routine childhood vaccination constitutes the most significant modifiable risk factor for ASD."
That quote from the Conclusion of the McCullough Foundation paper, says it all. The one thing that has increased it's impact on American kids at the same rate autism has afflicted them is vaccination.
Have a read at the above links. It's free, and the data is all publicly available, unlike the papers published by vaccine myth preachers that never compare autism and vaccines. Lying by omission is still lying, and we've been lied to for a long time. This is why vaccine manufacturers demanded immunity for adverse events from the Fed.gov. This is why the PREP Act shields them from liability, because they are causing autism. Here's the receipts.