jerkwater

We owe the colorful Americanism "jerkwater" to the invention of the steam engine - an advancement that significantly accelerated travel by rail but also had its drawbacks. One drawback was that the boilers of the early locomotives needed to be refilled with water frequently, and water tanks were few and far between. As a result, the small trains that ran on rural branch lines often had to stop to take on water from local supplies. Such trains were commonly called "jerkwaters" from the motion of jerking the water up in buckets from the supply to the engine. The derogatory use of "jerkwater" for things unimportant or trivial reflects the fact that these jerkwater trains typically ran on lines connecting small middle-of-nowhere towns.