 As the nation's railroad system expanded, large numbers of 'tank' ponds were built by damming various small creeks that intersected the tracks in order to provide water for steam engines; later, new towns often sprang up alongside these water stops.Shippers found that black bass were a hardy species that could be transported in buckets or barrels via the railroad, sometimes using the spigot from the railroad water tank to aerate the fingerlings.Largemouth bass were often stocked in tank ponds and warmer lakes, while smallmouth bass were distributed to lakes and rivers throughout the northern and western United States, as far west as California.