>The transition from coal to oil and/or gas for heating systems for homes and business. Was it mostly because oil and/or gas cost less or because it was easier to use oil and/or gas?<
Coal was delivered by dump trucks using chutes to slide coal into home basement coal bins. Coal was then hand shoveled into the furnace, primitively regulated and then ash disposal was required. Clearly, convenience of oil and natural gas was a hugh improvement, even though there may not have been a cost saving. During the Depression, people would go to the train tracks and gather coal that fell off the coal cars, I heard that, I wasn't there.
Guys: What 'goes around, comes around'! When I was a tyke (say early '50s) I remember my great-grandmother feeding coal to an old kitchen range - and there was a kerosene heater in the living room. Some deja vu: We bought an old farmhouse (ca. 1915) in the late '70s - still had one of those coal-fired kitchen ranges (but gas burners and oven). Biggest closing cost was all the oil in a 1,000 gal. underground tank. Thanks to the oil shortages and price spikes the following few years, we actually took a few coal deliveries after firing-up the range again. Also bought a kerosene heater for the living room. I still have about a ton of coal in the basement and I won't be too surprised if I resort to using it someday!