Trailer thefts are not uncommon, and there are several common risk factors and prevention measures for owners to consider.
Often the thieves are simply stealing them and selling them to pawnshops. Some are sold unwittingly to law-abiding citizens; others are sold directly to unscrupulous lawn/construction businesses, often with tolls still on them.
The most common risk factor is that these trailers are almost always plain white or black, usually completely unmarked. Most commonly taken are the small enclosed utility trailers, sometimes flat bed or open car trailers, less often full size enclosed car trailers, possibly due to the registration/tag requirements.
The stolen trailers are usually unattended at a jobsite, on business premises after hours, or easily accessible in someone’s yard.
There are several theft prevention measures available such as tongue locks, chaining wheels, and marking the trailer in an obvious manner.
Have a steel fabricator weld your name or company name and phone number onto an obvious part of the frame, it is relatively inexpensive to do and very time consuming to remove.
Mark trailers with special paint-jobs, decals, or lettering. Many owners are reluctant to so as not to attract thieves to the contents. Sometimes owners trade out trailers often and want to make them easier to re-sell. These are valid concerns, but by making obvious marking, it makes it much more identifiable, and lowers the chances of a thief being able to sell it. If you are considering decals, use 3M Scotchlite reflective decals like used on emergency vehicles. These decals are extremely difficult to remove, come off in little tiny chips, and will always leave a residual ghost image.
Spray-paint your name/phone number on the INSIDE in big, bright fluorescent paint. A buyer would see it and it would be hard to paint over because often fluorescents bleed through other paints.
Obtain state license plates for the trailer. This may cost a few dollars, but a thief may be deterred because there is a higher risk of them being caught in possession of the stolen trailer, and there would be additional paperwork that would be involved in trying to sell it.