Been trying to figure out how to an answer to these various threads about this subject. Cant find a way to post something that wont upset part of the membership, so ill just throw out some facts I've uncovered over the last 20 plus yrs of researching them. The old tractor and implement books state, a garden tractor is one that will pull a single plow of 12" or less. It doesn't state whether its to have one or 4 wheels. A lot of what's out there after 1965 are basically lawn mowers. Sure lots of them plow, but they fail in being able to work a garden after the crop is in and up, due to low clearances, just being to wide, or too heavy. As time and situations changed, the roles of the GT did also. At one point the roto tiller ate up a lot off GT market space, as people dint have the time or the space to till up half and acre. Few people in the early parts of 1900's needed a FEL, or even a 3pt hitch. I believe I counted one time that there were 800 different companies that built a GT of some kind or other. Some of them like the Stockton(a small crawler trac unit made in Calf.) never left there home area. My Mighty Man was built in Tacoma,WA, and didn't sell well east of the mountains. There are several more west coast units that stayed mostly around there home areas. Companies like Planet Jr, sold by mail order all over the world, from the early part of 1900's to at least the 1970's. Now true, there stuff was mostly seeders and cultivators, but they did make tractors in the 30's. Even as close as I am to South Bend, very few Wheel horses are found here. Galesburg, KS isn't really that far either, but most of the Shaw units here were imported from other states. From MN in the North came the Standard Twins, but most of them went to Pa or NY. A lot of what you find is directly due to what kind of stores you have around you, or if your in a market crop area. As I live in a rural area, there are tons of farm tractor dealerships here, and naturally you can find tons of Cubs, Massey, Deere, AC and MM units around. If you lived in a bigger city your choices were limited to some of the many MTD or Murray models, probably the Bolens, and wheel horses. There were a lot of tractors that came from JC Penny, Brown/Lynch/Scott, Western auto, Gambles, and other hardware type stores. Most were built by who ever they could get the best deal on left over parts with. There are many more examples than I care to write up.
Now not to promote Sears, but as a catalog company they were a powerhouse of mass marketing. Under the DB and Roper name they built 10's of thousands of tractors and attachments,(500,000 tractors by 1975) mostly in the same factory from 1933 to 1986. During the 30's to the 60's DB shipped boxcar loads of stuff to Sears branch warehouses all around the county, these warehouses in turn shipped "bundles" out the homeowners via the LCL(less than a carload) system on trains. The railroads ended this in the 60's and things went by truck freight. Sears also printed out many catalogs for the same year, that were regional. If you lived, say in Texas or NC, your copy didn't have a snowblade or snow blower listed, as they really weren't needed in that area. Montgomery Wards did some of the same things in there line, but unlike Sears they had Simplicity or Midland built the tractors, where as Sears owned the factories.
There is probably enough info out there to write up a book on the subject of Regional GT's and the men that made them. You could even include some info on the many different small gas engines that powered them over the last hundred yrs.