It is among the most mundane of routines: Arrive at a hotel. Enter the hotel. And when in Vegas, the rest is supposed to stay there.

But, when the rapper Meek Mill arrived at a Las Vegas hotel Saturday for a hotel club party, the rapper says he was stopped, told he could not enter the club or any other part of the hotel, and threatened with arrest. The hotel told NBC News that the incident "related to a matter of security, not race." The club — not the entire hotel — had reached capacity.

Mill’s lawyer has claimed the hotel maintains a list of banned black entertainers, a potential violation of federal civil rights law that he has threatened to pursue in court. The hotel did not respond, by deadline, to questions about the possible existence of a list but did say that Mill was turned away because of capacity concerns.

To some, it was the latest example of a problem that most prominently entered the headlines more than a year ago, when two black men entered a Philadelphia Starbucks for a business meeting and left the store in handcuffs after a manager reported feeling “threatened.” Since then, dozens of other black Americans have experienced the unpredictable hazards of eating, swimming, waiting, mowing, napping, banking, walking, biking, barbecuing, cleaning, working, commuting, flying, picnicking and shopping while black.

The problem, which has become a standing feature of almost every news cycle, has no geographic boundaries, and no pattern beyond the race of those subjected to scrutiny.

While these viral incidents are often dismissed as isolated examples of racial anxiety, experts say that the phenomenon points to something far more serious. This, they say, is modern-day segregation.

It is a way of dictating who is welcome in certain spaces and who is not. And, as with Jim Crow laws and the black codes before them, American police are playing a role.

“We’ve come to a place, whether they are eager to do it or not, where police are functioning as personal racism concierges,” said Phillip Atiba Goff, co-founder and president of the Center for Policing Equity at John Jay College of Criminal Justice, a division of the City University of New York. “And leaders of all kinds of institutions are searching for creative ways to both avoid calling these incidents what they are — racism — while appearing concerned.”

Over the past year, there have been several momentary solutions to the problem of everyday racism. A handful of people have been fired. Corporate executives have apologized. Workers have received bias training, and some police officials, social scientists and city leaders have urged caution in responding to 911 calls containing indicators of bias.

But more fundamentally, experts say, America must reckon with how people understand public spaces and who is seen as belonging there. Even without force of law or signs that say “NO DOGS, NEGROES, MEXICANS,” many Americans’ lives remain largely segregated.

“What we are getting,” Goff said about the many incidents of black people barred, issued trespass citations or forced into contact with police, “is information about what spaces are white, or prefer to be so.” He added, “If you are stopped, harassed, questioned, ejected each time you go to a place, that is a form of communication itself.”

‘Challenging and unacceptable experiences’

Earlier this month, Marvelyne Lamy, a charter school teacher, took a group of 25 middle school children to the Museum of Fine Arts in Boston. About 97 percent of the school’s students are black or Latino, and more than 60 percent are economically disadvantaged. This was supposed to be a bit of exposure to the arts that low-income families struggle to find the resources to provide.

Instead, during the students’ visit, guards trailed them through the museum, Lamy wrote in a Facebook post that created a media storm. When another museum visitor spotted a student dancing to music included in an exhibit, the visitor said, “it’s a shame that she is not learning and instead stripping,” Lamy wrote. Later, students told teachers that when they entered the museum, a staffer said, “no food, no drink and no watermelon” allowed.

Museum officials responded with dismay, saying the students had endured “challenging and unacceptable experiences.” After an investigation, the museum banned two patrons and said it will institute sensitivity training for employees. The employee accused of making the watermelon comment denied it, saying the warning was instead against “water bottles,” according to the museum, which also said the employee has since left the country. The guards who appeared to follow the students were changing shifts, the museum said.

Lamy said in an email to NBC News that “the museum's findings were a way to cover their tracks. They did not want to admit that our students were racially profiled and followed.” During a Boston radio call-in program, other black museum visitors spoke of similar experiences.

They remain common. A majority of black, Latino and Asian Americans say they have experienced discrimination because of their race or ethnicity, according to data released by the Pew Research Center in April. What’s more, 46 percent of black men and 40 percent of black women said discrimination had caused them to fear for their personal safety.

‘A big black guy’

That fear is what Lorne Green said he experienced after he walked into a Starbucks in Brandon, Florida, in April. Green, a public insurance adjuster, recalled hearing, above the din of cappuccino machines and table conversation, someone say, “There’s a big black guy headed for the bathroom.”

He said he had been in the bathroom for less than 10 minutes when a Starbucks staff member banged on the door and then called the sheriff. When he emerged, Green said he was angry and embarrassed and uttered two curse words as a Starbucks staffer yelled for him to leave. When Broward County deputies arrived, they interviewed only the store’s staff and issued Green a trespassing order barring him from the shop for 365 days, according to public records.

Green said that when he heard police had been called, he feared for his safety. “I did think: After all the attention, all that happened in Philadelphia, is there anything, really, that has changed?”

Starbucks said the company took Green’s concerns seriously and was investigating.

Whether or not companies, police or 911 callers admit it, prejudices are often at the root of these incidents. Sometimes they are overt and acknowledged, said Alexis McGill Johnson, co-founder of Perception Institute, a collection of researchers and activists who develop scientific methods to reduce discrimination. Other times, the people who set these incidents in motion are acting on “implicit bias,” an unconscious set of cognitive shortcuts and stereotypes, said McGill Johnson, whose organization was asked for help by Starbucks last year after the arrests in Philadelphia.

On top of this, some people operate with heightened levels of what McGill Johnson called “racial anxiety.” That is a fear that people unlike oneself embody danger.

While stereotypes and security concerns are often used to defend discriminatory actions, they don’t have a basis in fact, said Jerome Williams, a consumer psychologist at Rutgers University-Newark who has researched what he calls “retail racism” for more than 25 years.

In one case, Williams found that black people made up 10 percent of a department store’s customers but 90 percent of those stopped by the store’s security team. The store’s explanation: Security was in place to prevent shoplifting.

There is no evidence that black Americans steal more often than anyone else, Williams said. There is evidence that black Americans are more closely monitored and more often accused, then more often arrested and prosecuted by a criminal justice system with well-documented biases.

“At least as telling as the constant barrage of stories about African American people stopped, suspected, harassed, is the constancy of denial about what is happening,” Williams said.

What the law says

Federal and state civil rights laws are clear: Public spaces and certain businesses, including museums, restaurants and hotels, must serve the entire public without discrimination, said Dariely Rodriguez, director of the Economic Justice Project at the Lawyers’ Committee for Civil Rights Under Law.

But that’s often not the case, particularly in privately owned spaces open to the public, where the preferences of owners, workers and customers can quickly take priority over basic equity, Goff said.

“Those the business owner and other customers believe can pay, who ‘fit’ with the business’ aesthetic, won’t face deep scrutiny or extra monitoring,” Goff said. “Those who don’t will. But, in the United States, it’s unrealistic to assume that who belongs where, and who or what doesn’t, will not ultimately involve race.”

In other words, people paying for a $6 cup of coffee want what they see as a $6 coffee experience. Then, they take that same notion with them to parks, to museums, even when evaluating people walking down their street.

‘Excuse me. Excuse me, sir.’

Alexander McNab, who graduated from Columbia University in May, has wondered to himself why he was so often asked to show ID at Columbia and Barnard, an adjacent and affiliated college. White students typically breezed by. In April as he walked into Barnard’s library, he heard the request again:

“Excuse me. Excuse me, sir.”

He kept moving. Silent compliance hadn’t worked in the past. Before he could ask why he was being stopped, he was surrounded by multiple officers, lifted off the ground and pinned to a counter. Cellphone video of the pin-down went viral. The school suspended the public safety officers and supervisor involved with pay and apologized to McNab in a private meeting.The school also hired an independent firm to investigate.

During his meeting with Barnard officials, McNab said, the school pressed him for a to-do list. In his view, this was an attempt at a quick PR fix, not a commitment to developing policies and equally applying them.

“It’s the act of existing that puts some people on edge,” McNab said. “We exist in these spaces where people expect, whether they admit it or not, where they just feel more at ease if everyone is white.”