Recent examples in the United States of national protests would be the current Black Lives Matter protests of police brutality, the Occupy Wall Street protests of economic inequality, and the Antiwar protests against military intervention in Iraq and Afghanistan. Although it could also be argued that these are also examples of international protests, they all, most certainly, had domestic roots in the United States.
Black Lives Matter began in 2013 as a social media response to the acquittal of George Zimmerman for shooting an unarmed black (male) teen to death. By 2014 demonstrations began in New York and Ferguson -- as a continued response to the criminal justice system that structurally perpetuates racism - and further spread, by the summer of 2015, to cities across the country, including Chicago, Cleveland, Madison, San Francisco/Oakland, Newark, Cincinnati, Austin, Baltimore, Sacramento, Minneapolis, and many more.
Occupy Wall Street, although seemingly local with a slogan that references its origins in New York, the protests targeted at the concentration of financiers and bankers particular to Wall Street in late 2011 - soon spread across 600 separate sites in the US alone. Unsurprisingly emerging on the heals of the 2008 recession and the bail out of the big banks, students and the working class alike mobilized together in the name of the 99% - as a juxtaposition to the increasing concentration of wealth in the hands of the top 1%. Antiwar protests against the invasion of Iraq in 2003 and Afghanistan in 2001 have mobilized in cities that include New York, San Francisco, Washington D.C., Austin, Colorado Springs, Seattle, Philadelphia, Chicago, and others. Although these protests peaked in 2003 and consisted of 36 million protests worldwide (at its largest), demonstrations of fluctuating size have also continued into the present. Interestingly, these contemporary antiwar protests are also reminiscent of what is still considered the largest national (political) demonstration in the US, the Anti-Vietnam War protests of 1969.