lots of 2 foot in mining and lumber, even internal iron and early steel RR's..... no trucks back then, for any heavy hauling, only dobbin..... Other than by horse and wagon, there weren't no other technology there for a long while, for long hauls or short....and well, they built whatever worked for whatever they needed to move, using what they could afford.

Lots of "rail" lines from 18"to 24", to 30 inch gauge, were used too There ain't much that's not flat about the Carson and Colorado or the original NCO which were built as 36" gauge lines. You have a lot of 42" and meter gauge in a lot of places out side of the US, including huge systems in Southern Africa and India. The benefits of a wider gauge were early on more apparent, which is why many NF lines were standard gauged. But even in CA there were plenty of weird gauges in the early logging and mining ops, up until the 1920's.

Different sizes come with different price tags for different kind of uses, back when you didn't have trucks and your choice was a horse that had to be fed, and could do 1/20th of the work. They built narrow gauge logging roads all over the place, where there were trees, flat or mountains, and used narrow gauge. Economics and available technology were what drove early choo-choo's just like today. Even today, like at Plaster City, it isn't about topography.

Maine was a pretty remote place, even back then, it started logging early, and many of these were upgraded "horse lines", built to have teams pull loads along tracks (choo-choo tracks was around to help haul heavy loads way before the choo-choo engines were to pull them), and sometimes these were adaptations. A lot of early narrow gauge horse car lines became default narrow gauge trollies when they got that new fangled electric motor, so LA had 42 inch gauge trollies. Only a few of these lines had things like the cool passenger cars and such that we like foam over today, most of these were "bare bones" industrial operations, bring logs into the mills, or the harbors, so they could be milled or shipped out.

Then trucks came along, which were cheaper and way more productive than horses and wagons, and were also much cheaper than building and maintaining a complex system of choo-choo tracks to service these industries..... As trucks got bigger, more powerful, and more reliable, topography became even less of a reason, as mountain construction was expensive even for narrow gauge RR's.

Wider gauges allow for heavier larger veh9cles. But, a discussion of wider gauges may entail us becoming involved in BART like webs of deceit and intrigue, so it's good you asked about narrow gauge.