An immigration rights march that drew thousands of people of all ages and races was marred by a car that struck a group of marchers at a downtown intersection.
Demonstrators surrounded and began beating on the car after it hit and slightly injured three people Monday afternoon, and the driver was arrested for investigation of assault, said police Officer Debra Brown.
Five other people were arrested for possible weapons violations and one person for obstructing police, Brown said.
Police would not give an official estimate of Monday's crowd, while estimates by organizers ran from 30,000 to 65,000.
"Elite politicians ... have awakened a sleeping giant," King County Council member Larry Gossett told an evening rally at the Federal Building in Seattle. "Everybody, we're all united in this effort to get comprehensive immigrant rights."
Elsewhere in Washington, rallies drew crowds estimated at 5,000 to 8,000 by police in Yakima and about 5,000 in Pasco, and hundreds of others marched and rallied in Tacoma, Olympia and Bellingham.
In Yakima, immigration rights activist David Gutierrez lauded the size of the crowd at Miller Park.
"Not even in the time of Cesar Chavez, may he rest in peace, did this many people come out in the Yakima Valley. Some people don't want us here, but we're staying. The economy depends on us," Gutierrez said.
The late Chavez, co-founder of the United Farm Workers, led a march of 700 people in the lower Yakima Valley in 1986.
An immigration rights march and rally April 10 drew 15,000 people in Seattle.
On Monday, demonstrators waved large American flags and signs that read "Stop the war! Open the borders" and "Equal Rights (not) Special Rights."
Couples walked arm-in-arm beside teenagers and mothers who maneuvered baby strollers through the throng that at one point stretched more that eight blocks.
Spanish teacher Marta Buell, 36, of Seattle, came to the United States 12 years ago from Mexico and became a citizen in 2001.
She said the process was easy for her but some of her friends have been deported.
"I've seen how the families get broken up and the kids suffer," Buell said.
Nationwide demonstrations and boycotts Monday were organized by activists angered by moves in Congress to criminalize illegal immigrants and fortify the U.S-Mexico border.
"We're all immigrants in this country. It's not just about the people who just came here recently," said Rebecca Chan, 31, of Seattle, a board member of the Seattle chapter of the Organization of Chinese Americans.
"This is really about all of our rights and not just about immigrants who are here. It's a debate about what America is going to be," said Pramila Jayapal, founder and executive director of Hate Free Zone Washington.
Michael Blanton, 46, a lawyer in Olympia who specializes in Social Security cases, said he was happy that the Seattle crowd included Whites as well as people of color.
"I just think if people want to come here and do jobs a lot of Americans don't want to do ... more power to 'em," Blanton said.
Much of the debate has focused on legalization of undocumented workers, but Jayapal said comprehensive immigration reform also must address family reunification, civil and human rights and worker protection.
Jayapal, who was 16 when she came to the United States from India 20 years ago to attend school, noted that families often must wait an average of 10 years to bring a relative into the country while a number of U.S. Labor Department studies estimate the country's worker shortage at about 500,000.
"We're still operating with a system that acts like we don't need to bring in additional workers," she said.
Tyson Foods' meatpacking plant in Pasco was one of about a dozen of the company's operations that were closed Monday, but it was business as usual at most of the company's more than 100 plants nationwide.
"We have not encouraged workers to join the rallies although we certainly understand the sentiment behind them," said Gary Mickelson, spokesperson for Tyson Foods in Springdale, Ark.
At La Tarasca restaurant in Centralia, about 25 miles south of Olympia, owner Manuel Ayala expressed mixed feelings while turning away customers Monday. His five workers told him Sunday night they weren't coming to work.
"They need opportunities to make a living here. The law affects these people," he said.
"This is a small business," Ayala said. "I'm losing money. What I can I do?"
— The Associated Press