In the USA any course length can be certified. As a matter of fact, for the 3 km distance, 61 courses have been certified. Certification is for more than records. When I was a runner, I knew I'd never set a record, but I cared a lot about whether the course was accurate. Certification gave me that assurance.
Anyone wishing to get the really complete information on what’s certified in the USA, and what’s not, should go to the website www.rrtc.net and download both the active and archive lists of certified courses. All 23,000+ courses are there, along with when they were certified and who measured them.
The list helps a lot when you are looking for a course.