I'm glad you enjoyed looking at the old ND and SD plates.
The earliest SD was 1913 and ND was 1911, but many towns in ND and SD issued their own plates as early as 1903 so it is possible to find a 06 or 08 with an ND or SD on them..... I collected plates as a youngster and had hundreds when I went into the military - mainly Iowa, Nebraska and Michigan.. My Dad sold them for next to nothing as a single lot, when he sold our farm in Michigan in 1980. I always saved license plates, but didn't get back into looking for them until the past couple years. I have SD from 1920 to 1975 minus 21, 38, 43, 44, 45 ,51 and 53. I have a few ND, but not a lot. the rest are an eclectic mix of years and states plus several countries, territories and Tribes... I mainly enjoy finding old, rusty, crusty ones that I can paint back to the way they were.