Know-Nothing Riot

The term Know-Nothing Riot has been used to refer to a number of political uprisings of the Nativist American Know Nothing Party in the United States of America during the mid-19th century. These anti-immigrant and anti-Catholic protests culminated into riots in Philadelphia in 1844, St. Louis in 1854, Cincinnati and Louisville in 1855, Baltimore in 1856, Washington, D.C. and New York in 1857, and New Orleans in 1858.
Know-Nothing Riots (1844-1858).
Cincinnati Riot.
The Election Day Riots of 1855 occurred in Cincinnati between April 2-7, 1855. The election was between James J. Faran, the Democratic contender and editor of the "Cincinnati" "Enquirer", and James D. Taylor, rabid nativist editor of the "Cincinnati Times". Rumors of illegal voting, ballot-box stuffing, and naturalized voters preventing native-born citizens from voting sparked the events. 
Baltimore Riot.
See Know-Nothing Riots of 1856
New Orleans Riot.
The New Orleans Know-Nothing group began as a local movement in 1858 to reduce what residents considered a high rate of crime and violence in the city, primarily among Irish and German immigrants, who were among the poorest classes. A secret Vigilance Committee was formed to monitor their activities, and in particular to prevent disruption of upcoming municipal elections.
On the night of June 2, 1858, armed men under the command of Capt. J.K. Duncan, an officer in the United States Army, marched to Jackson Square and occupied the court rooms in The Cabildo. For the next five days, a standoff existed between the Vigilance Committee and members of the Native American Party. On June 7, the elections were held and the Native American candidate, Gerard Stith, defeated the Democratic Party candidate, P.G.T. Beauregard. The Vigilance Committee disbanded with no further violence.