Officials expect almost 1 million people to attend Donald Trump’s Jan. 20 inauguration — and they also worry about the potential arrival of hundreds of thousands of protestors who are expected to attend a protest march the next day.

“Obama drew an estimated 1.8 million people to the National Mall eight years ago, according to federal and local agencies. Planners say they are expecting no more than 900,000 people to attend Trump’s ceremonies Jan. 20,” NBC reported.

The military is using a 60 feet x 40 feet map to map out January 20 inauguration activities.

LIVE on #Periscope: 60 feet x 40 feet map used by DC area military to map out Jan 20th Inauguration activities. (at… https://t.co/oHuoHtP5uG — Tom Sherwood (@tomsherwood) December 14, 2016

“Obama drew an estimated 1.8 million people to the National Mall eight years ago, according to federal and local agencies. Planners say they are expecting no more than 900,000 people to attend Trump’s ceremonies Jan. 20,” NBC reported.

Meanwhile, varying crowd estimates were provided by different sources. According to NBC, the D.C. Department of Homeland Security and Emergency Management is reportedly planning for 800,000 to 900,000 attendees attend at the swearing-in ceremony and inaugural parade, while the U.S. Armed Forces Joint Task Force-National Capital Region (JTF-NCR), is expecting 800,000 people and the Joint Congressional Committee on Inaugural Activities (JCCIC) has suggested 750,000 people would be present.

Some have suggested the inauguration could see up to 750,000 demonstrators, partly because many people are expected to attend a formal protest march the next day.

Hundreds of people involved with the planning process reportedly gathered Wednesday for a day-long rehearsal and authorities will also be on alert for the “Women’s March” on Washington the next day. Nearly 200 progressive groups have signed up for the protest.

Katy Perry, Cher, Scarlett Johansson, America Ferrera, Zendaya, Amy Schumer and Chelsea Handler will also participate in the protests.

Obama’s 2013 inauguration reportedly saw approximately 1 million people. Bill Clinton’s 1993 inauguration saw 800,000 guests and George W. Bush’s 2005 inauguration had 400,000 attendees.

Security costs for the event have already crossed $100 million, according to the International Business Times. There will reportedly be over 3,200 police officers, 8,000 members of the National Guard and nearly 5,000 active-duty military members monitoring the day’s proceedings in the nation’s Capitol. The Capitol Police, FBI, Secret Service, National Park Service and National Guard, will reportedly be covering the events.

“Dealing with protests and demonstrations is something we deal with all of the time,” said Chris Geldart, director of D.C.’s Homeland Security and Emergency Management Agency, according to the IB Times. “We will see more protesters here than we have seen in past inaugurations. But we will be ready.”

Follow Adelle Nazarian on Twitter and Periscope @AdelleNaz