Some Trump supporters also showed up to voice their agreement with his stance on immigration.
Hundreds of protesters chanting "This is what democracy looks like" marched through Salt Lake City.
Suzanne Martley was the chief organizer of the "Not My President" rally and said the day provided a ideal opportunity to express the expectations people have for the presidency.
Protesters in cities across the country took to the streets on Monday for "Not My President's Day" rallies with a strong anti-Trump message.
The Salt Lake Tribune reports that the crowd marched to push back against Trump and his administration's stance on such issues as the environment, immigration, free speech and Russian Federation.
The Stop Trump coalition has hired a permanent staff member to coordinate protest efforts, with £16,000 raised via crowdfunding and £10,000 donated by the trade union Unison.
But in a telephone interview with cleveland.com, King stressed that the rallies are not about specific sponsors or organizations.
"While we acknowledge that Donald Trump holds the current title, the policies he's trying to put in place are not the beliefs shared by the majority of the people".
"Nope. It's not about them", he said.
Another week, another series of demonstrations by opponents of President Donald Trump.
"This is literally grassroots", King said. "If people can get involved in local issues then that's a positive". "That's what it's about".
Organizers for Monday's rallies asked protesters to tweet with the hashtags #notmypresident and #doyourjob at 2 p.m. eastern time. Others are listed in Cincinnati, Mansfield, Springfield, Jackson and Bridgeport.
"Our hope is that this mass movement can swing public opinion on a range of issues in a way that progressives have never managed before, and on issues on which we have been losing for decades", the group's spokesman said. But organizers in Tennessee have announced a program and agenda for their Nashville rally March 4, including an appearance by an Ohio Tea Party leader, Tom Zawistowski of Portage County.
The Rapid City rally was far from the only one.
"When he and his minions chose to put forth an unconstitutional ban on Muslims entering the United States, we went to court and were able to stop it", Ed Yohnka, of the Illinois American Civil Liberties Union, told the crowd. "Let's rally while our federal representatives are back in California and remind them who they represent".