Some of youse folks have never been "out west," because that nasty stuff is everywhere...well, not much in the cities, but certainly in outlying areas.
Here in the Kahleeforneeya's Central Valley, the stuff clogs irrigation systems on a regular basis. Most irrigation districts have a crew dedicated to cleaning it out of grates, gates, and other places where it collects.
We can thank farmers who brought it in in the 1800's mixed with wheat seed, as well as the government who brought it in, thinking it would be good cattle feed in some of the more barren lands...