Just wondering if ultralight aircraft in the United States have tail numbers like the larger general aviation aircraft have?
Notwithstanding any other section pertaining to registration and marking of aircraft, ultralight vehicles are not required to be registered or to bear markings of any type
In the USA: "ultralight aircraft" as in having an engine or two? Yes they do. Pretty sure anything larger than an 8 oz drone needs to be registered to fly in the US airspace. Hang gliders and parachutes are about the only thing not needing a tail number. I'm sure someone here can find the appropriate FAR paragraphs with the details from www.faa.gov My internet is awfully slow today.
I may have overstated things above. Found this article at the United States Hang Gliding and Paragliding Association website, which seems to state that "true ultralights" may not need to be registered, and has quite a few reference links at the bottom:
January 31, 2008 is the deadline for converting overweight or two-place ultralights used in our current fleet of tugs to FAA-registered E-LSAs. After that date, it will not be possible to convert an existing unregistered tug to an E-LSA. An overweight or two-place ultralight tug that is not converted to an E-LSA by January 31, 2008 can continue to be flown until January 31, 2010, but after that date that it cannot be flown at all, as the FAA will consider it to be an unregistered aircraft without an airworthiness certificate. Very light tugs that actually meet the definition of a true ultralight may continue to tow hang gliders under Part 103 rules, without being N-numbered, as long as USHPA's aerotowing exemption #4144 remains in effect.