Transcript for Tulsa braces for 'civil emergency' after Trump rally postponed
And it's great to have you with us as we near the end of another week together. We begin tonight with the news from tutulsa, Oklahoma. Authorities declaring a sieve emergency ahead of president trump's campaign rally tomorrow tonight on this juneteenth when this country marks the end of slavery in the U.S., the continued push across this country for justice. In New York City tonight, people marking the juneteenth holiday by marching across the Brooklyn bridge. In Denver they marched from the martin Luther king monument to the state capital. Thousands showing up for racial justice. And in Tulsa, the scene of the worst race massacre in U.S. History they carried a empty casket. Some of trumps supporters gathering tonight waiting for tomorrow night's rally which had been scheduled for tonight. The president moving it touchdown white house saying out of consideration for the juneteenth holiday. Tonight, the president's message to protester who is he believes might try to disrupt his rally. ABC's Marcus Moore leads us off from Tulsa. Reporter: In Tulsa tonight, president trump's supporters lining up for blocks to get inside tomorrow's rally, some camping out for days. We're here to support him. It's history making. Reporter: The event was first scheduled for today juneteenth, a date reserved to commemorate the end of slavery. After an outcry, president trump postponed the rally to Saturday, later claiming in an interview with "The Wall Street journal" that he, quote, made juneteenth very famous, adding that nobody had ever heard of it. Today in Oklahoma, a March through what was once known as black Wall Street, Tulsa's Greenwood district. This historic black neighborhood, the site of a 1921 massacre where a white mob killed at least 300 residents. Hundreds of homes and businesses burned to ground. It sits less than a mile from Saturday's planned rally where up to 20,000 people could pack this arena. The mayor bracing for the crowds, declaring a civil emergency. The president today issuing a warning via Twitter, writing, any protesters, anarchists, agitators, looters or lowlifes you will not be treated like you have been in New York, Seattle, or Minneapolis. It will be a much different scene. Four more years! Reporter: This is trump's first rally since the pandemic began. Oklahoma hitting a record number of coronavirus cases just yesterday. Those attending the rally required to sign a waiver agreeing not to sue if they're exposed to the virus, but most supporters we met are not deterred. I personally am not going to wear a mask. It's our option, our choice to wear a mask. I trust our immune system. We're talking about tens of thousands of people inside the bok center. Are you worried at all about the spread of this virus? I'm concerned about it, yes. I've got to step out of my comfort zone and get here. Just to support Donald Trump. Reporter: The white house says there will be temperature checks, hand sanitizer and masks at the door, but there's no requirement to wear them. We have been spiking since last week. I'm not talking like this. I'm talking like this. It's going straight up. All this can do is take us this way or this way, over the top. Reporter: As city leaders in Tulsa prepare for a massive rally, thousands more celebrating juneteenth from coast to coast. This represents our future. Reporter: No Oakland, work holted for hours to protest racism. And crowds marching across New York's Brooklyn bridge. Marcus Moore back with us tonight from downtown Tulsa. I know the state supreme court today ruling on this rally? Reporter: That's right, the supreme court here denied a request to stop this rally and David, there's a lot of energy here in downtown Tulsa. We have seen speakers on mega phones talking to crowds gathered in the streets. There was a curfew in place this weekend for downtown Tulsa, but the mayor says he rescinded that order at the request of the secret service. Marcus, thank you. As this country marks juneteenth, the holiday that celebrates the end of slavery in America, the new push all over this country to learn more about our country's painful history. What we uncovered from the archives. The interview and some powerful words and a note about what will happen here later in evening.
This transcript has been automatically generated and may not be 100% accurate.