sentences:  Magruder's term as mayor was mostly marked by improvements to the city's infrastructure, in particular building an archway over a stream that then ran near L Street and frequently overflowed, damaging the city streets.He did, however, deal with the crisis of the June 1857 Election Riots, in which the Know-Nothings recruited a street gang from Baltimore, the Plug-Uglies, to come to Washington on its local Election Day and intimidate the voters at the polls; the Plug-Uglies turned away anti-Know-Nothing voters with rocks, guns, and knives, until some citizens brought weapons of their own and the violence grew into mob rule.When the rioters reached levels of over 1,000, Magruder closed the polls and requested military aid from President James Buchanan.