I am getting notice that I now have to get my boat trailer inspected? Who does this and when did this start?

Started this year (Mar 1 I believe). Trailers with a gross weight exceeding 4,500 lbs. must pass an annual safety inspection. Registration is required for all non-farm trailers operating on public highways. Registration and titling requirements vary according to trailer type and weight. Homemade trailers under 4,000 lbs. gross weight are not required to have a Vehicle Identification Number (VIN) unless they are going to be titled. Most utility trailers fall into two categories: Manufactured (built by a trailer manufacturer) or homemade (built by an individual in their garage or shop). In addition, trailers are categorized by gross weights (the trailer weight plus the weight it can carry) under and over 4,000 lbs. Bring it to a Auto inspection site and they will inspect it.