It depends on your location and time frame of course. If you go back to the origins of the railway in mid-19th century Britain, they did become the main, dominant form of long-distance travel for some time, and it wasn't really until the postwar era in the UK that they lost that dominance to a combination of increasing car ownership and forces-surplus lorries and aircraft (particularly the Douglas DC-3) coming onto the market which helped road hauliers and small airlines get a start. This had already happened to an extent post-WW1, but the aircraft in particular were much more primitive.

It's a little more out of my area of expertise, but the rise in private car ownership which drove the choice of the road as a primary form of transport over public transport was IIRC down to a post-WW2 economic and social climate in the US that valued individualism and independence, coupled with an economic and manufacturing boom. In Britain, the primary driver away from railways in the post-war era was more to do with the ramshackle, bombed-about nature of the service by the time it was nationalised in 1948, with some locos and coaches even going back to the turn of the century - uncomfortable and unreliable, and the whole system generally dreary and unloved.

Christian Wolmar's Fire and Steam is a good general history of the railways in Britain.