This week, video of a white police officer's response to a complaint about black teens at a pool party in McKinney, Texas, went viral, because it struck many viewers as shockingly violent and disproportionate.

The backstory only made the footage more troubling. According to several accounts, police were called in response to a fight that broke out when a white adult told the black kids, some of whom had hopped the fence to attend the event, to "go back to Section 8 [public housing]."

To many, the story is just another addition to a recent series of high-profile incidents in which police have been accused of misconduct against African-Americans, a topic that has made regular headlines since the police shooting of unarmed black 18-year-old Michael Brown in Ferguson, Missouri.

But the setting here — a swimming pool where black kids were swiftly identified as outsiders and reportedly subjected to racial hostility for daring to be there, whether they were invited guests or not — means it has its own unique context.

There's a case to be made that the very existence of private pools like the one in McKinney was a response to the end of legal segregation of municipal pools in the late 1940s and early '50s. In other words: many white people preferred to build their own pools than enjoy this type of recreation side by side with their black neighbors.

That's according to Jeff Wiltse, the the author of Contested Waters, a book about the history of controversy surrounding America's public pools.

In a 2007 interview with NPR's Michel Martin, he provided this interesting piece of insight into the anxiety around intimate contact with black people, which he said made resistance to integrating swimming pools even more contentious than integrating schools in some cases:

And so the concern among white swimmers and public officials that if blacks and whites swam together at these resort pools in which the culture was highly sexualized, that black men would assault white women with romantic advances, that they would try to make physical contact with them, and that this was unacceptable to most northern whites ... ... There was a court case that emerged added an attempt by the local NAACP to desegregate the municipal pools in Baltimore. And this was right after Brown v. Board of Education. And so the local attorney argued that, well, schools may be being desegregated, but we can't have swimming pools be desegregated because swimmers come in potentially intimate contact with one another. And so a federal judge upholding racial segregation of Baltimore pools reconciled his decision with the recent Brown v. Board of Education decision by claiming that pools were more sensitive than schools, and that to integrate a swimming pool would not just potentially, likely lead to race riots and all sorts of violence. And so in the interest of the public good it was reasonable to keep swimming pools segregated along racial lines, even though the Supreme Court had ruled separate but equal was unconstitutional at schools.

(You can listen to the entire interview or read the transcript at NPR.)

There's of course not legally enforced racial segregation anymore, and it's doubtful that any of the white residents of McKinney — even the one who allegedly directed the kids back to Section 8 housing — would say they were squeamish about physical contact with African Americans.

But the residential segregation that made it possible for the black kids who were seen as outsider the pool to be so easily identified, and for their presence to cause such intense offense, is a reminder that some of the sentiments that fueled separate-but-equal swimming in this country still linger.