What states allow passengers to ride in trailer?

As of my last knowledge update in October 2023, states like Idaho, Montana, and Wyoming allow passengers to ride in trailers under certain conditions, often requiring the trailer to be designed for such use. However, regulations can vary significantly by state, including age restrictions and safety requirements. It's important to check the specific laws in each state, as they can change and may have additional stipulations. Always prioritize safety and compliance with local regulations when considering riding in a trailer.