I have a rough understanding of the 19th Century militia system in the US, and it seems to me, that lacking a Victorian SWAT team, that in cases of riots the local militia or homeguard were called out to put down riots, given as police lacked the ability to do so. Is this correct? Did US police forces maintain an ability to properly take on riots, or was this left to the home guard and militia?
Sorry /u/mosin91 you post a very interesting question that I would love to dive more into, but vacation is in less than 30 hours! I did however make a post some time ago discussing the riots in Baltimore that lead to the death of Robert E Lee's father, it should offer you some insight into the limitations of the militia to quell riots. I would note however that after the War of 1812 the militia largely went into a rather dramatic decline, dropping off considerably in usefulness.
My understanding is that state National Guards troops were typically called in by the governor of that state to disperse riots in the second half of the 19th century. Cavalry organizations in particular might be thought of as the SWAT teams of the 19th century, tasked with intimidation and violent dispersal of riots, protests and especially strikes. [Here is a brief account of a New York National Guard cavalry officer dispelling an 1895 streetcar strike in Brooklyn, and it happens to include a reference to a similar incident in Buffalo in 1892 . ] (http://books.google.com/books?id=50pZo6CzcAUC&lpg=PA148&ots=_ExBYVPfOM&pg=PA147#v=onepage&q&f=false)