Residents demand relaxation of infection prevention measures despite signs it is too soon to reopen.
Protesters have taken to the streets in states across the US, demanding that governors reopen economies shut by the coronavirus pandemic.
Rallies in Arizona, Colorado, Montana and Washington state took place on Sunday, following earlier protests in half a dozen states.
Agitation for easing restrictions has grown, despite the risk of a Covid-19 resurgence posed by reopening too soon.
US President Donald Trump has signalled support for the protests.
The US has become the centre of the Covid-19 crisis, with over 735,000 cases and some 40,000 deaths - but signs have emerged that it is reaching the apex of the outbreak and that infection rates are slowing in some states.
In Washington state, an early US virus hotspot, hundreds of people gathered in the state capital, Olympia, to demand the governor relax rules restricting the economy.
Police estimated the crowd at 2,500, making it one of the largest protests in US states against lockdowns over the past week, Reuters news agency reports.
Many of the protesters ignored social distancing guidelines, as well as pleas from rally organisers to wear masks.
Montana saw a few hundred protesters at a rally held in Helena, the Associated Press news agency reports
There was a similar-sized protest in Denver, Colorado, where protesters descended upon the state capitol building to demonstrate against the social distancing orders.
As protesters clogged streets with cars, healthcare workers in scrubs and face masks stood at crossroads in counter-protest.
Dozens of cars circled the capitol, local media report, while roughly 200 people assembled on the lawn, waving signs and flags.
In Arizona, protesters also took to their cars - estimated to be about 100 - and drove in circles around the state capitol in Phoenix to create gridlock, reports say.
Governors in several states have begun discussions to plan reopening amid signs of the slowdown, but other regions remain under strict lockdown.
California Governor Gavin Newsom was the first in the nation to issue a state-wide stay-at-home order, shuttering the country's most populous state since 19 March. Neighbouring west coast states Washington and Oregon followed suit days later, putting their combined 11.5 million residents under a stay-at-home order since 23 March.
New York Governor Andrew Cuomo announced this week that the state would extend its stay home measures until 15 May. Speaking at his daily virus briefing on Sunday, Mr Cuomo urged caution to residents, beset with "cabin fever" and desperate for their state to reopen.
"We still have to make sure we keep that beast under control," Mr Cuomo said. "As we all get very eager to get on with life and move on."
"This is only halftime in this entire situation."
Mr Trump, a Republican, appeared to endorse protests against strict lockdown measures, which are needed to curb the spread of the virus. He said on Friday that orders in place in Minnesota, Michigan and Virginia were "too tough".
Washington Governor Jay Inslee called the president's support of the protesters "dangerous", tantamount to encouraging "insubordination" to state laws.
"To have an American president encourage people to violate the law, I can't remember any time in my time in America we have seen such a thing," he said on ABC news on Sunday.
Nancy Pelosi, the Democratic Speaker of the House, accused Mr Trump of endorsing the protests as a "distraction".
"The president's embrace of it as a distraction from the fact that he has not appropriately done testing, treatment, contact tracing and quarantine," she told ABC.
On Saturday, protesters gridlocked the streets of Annapolis, Maryland, honking car horns in protest of lockdown measures. More than 200 people rallied outside the residence of the Indiana governor, while about 200 gathered in Austin, Texas. New York state also saw disruption.
Further protests are expected on Monday. BBC