It was just seven days ago -- even if it feels like seven years ago -- that the United States of America celebrated its 240th birthday. There were shout-outs -- from the perfunctory to the heartfelt -- to the principles of life, liberty and the pursuit of happiness that were truly revolutionary ideas when Thomas Jefferson put them down on paper, one block from where I'm sitting right now in the heart of Philadelphia.

But when the time finally came for the grand finale of bombs bursting in air, a thick, dewy gray blanket of fog had descended over the original 13 colonies, from Washington's Tidal Basin to the once-tea-soaked shores of Boston Harbor. Red, white and blue explosions hid behind the cloudy inversion like the blizzard of a bad 1950s TV signal, blurred, out of focus, barely visible. Public television switched to re-runs of fireworks from cloud-free July 4ths of yesteryear. It all seems a grand metaphor for a country that is in a fog, squinting for clarity and the joy of color.

The newest seeds of national discord were about to be planted in Baton Rouge, Louisiana, just three hours later. That's where an 37-year-old itinerant CD seller and father of five named Alton Sterling was pinned to the ground and then shot by police officers responding to a complaint that Sterling had a gun. The very next day in the suburbs of Minneapolis-St. Paul, Philando Castile -- a popular school cafeteria worker who had no criminal record and was licensed to carry his concealed weapon -- was shot and killed by an officer during a traffic stop; his girlfriend, Diamond Reynolds, calmly and surreally posted the aftermath live on Facebook, a shared moment of horrific intimacy that seemed to merge America's bloody past into a shockingly dystopian present.

On July 7, the nation's despair deepened exponentially in downtown Dallas when an extremist with a military background and a hatred of white people launched a sniper attack on cops who'd been protecting a peaceful protest march, killing five of them and wounding seven more. The echoes of his cowardly assault were heard two blocks away in Dealey Plaza, where a sniper attack on an American president nearly 53 years ago started folks asking pretty much the same things people are asking each other in 2016. Why is American culture tainted by so much violence, so much discord, so much hate?

It's a complicated picture. From the jetliner view at 37,000 feet, things don't seem to be that bad. The economy is better off than it was eight years ago -- a hard sell, I know, to members of the shrinking middle class who work two or three jobs to avoid becoming a statistic -- and the president who oversaw that era is about as popular as a POTUS can get in the red state/blue state era. Oh, and did I mention that he's an African-American, a symbol of the doors that have opened for non-whites since the 1960s? Crime -- regardless of what you might think -- is down over the long run, and parts of cities, like the bustling parts of Philadelphia with towering construction cranes that I can see from my Center City window, are said to be "coming back."

But this glass is also more than half empty. Increasingly, Americans are wondering about the things that don't jibe with our perception as the world's exceptional nation, a shining city on the hill. In some key measures, the United States is exceptionally weak. How could a country hold itself up as the greatest nation on the planet when it imprisons its citizens at a higher rate than any other developed country -- and it's not even close? Or when America is on the list with barbarous nations like China or Saudi Arabia as one of the few countries with the death penalty? Or when when the kind of heart-wrenching mass gun murder that might happen in another nation once in a generation -- if that -- seems to happen in America every six months. What sense does it make that the U.S. -- as measured by its gross national product, anyway -- remains the wealthiest nation on Earth, and yet our ranking for how students achieve in school and the quality of our health care is so mediocre?

Isn't the fact that millions of Americans -- enough for a leveraged-buyout takeover of one of our two political parties...the one that formally ended slavery and won the Civil War -- have rallied behind a candidate who routinely appeals to racism against Mexicans, Muslims, Native Americans and whoever else pops into his burnt-orange brain proof-positive that something has corroded our national soul. We live in a mass-media culture where perception is the reality, and the perception is that America isn't just on the wrong track but hurtling down a steep ravine. The first week of July 2016 just made that perception all too real.

As always, there's no one or even two things upon which you can blame our current...malaise (there, I said it.) Income inequality and flaws of a 21st Century capitalist system that's great at creating wealth for the few and lousy at creating meaningful work for the many is always lurking as an issue. But when you look at what's really behind America's increasing civic unrest, and the things that are driving people out into the streets -- whether they're marching for Black Lives Matter or cheering Trump's neo-fascist "Get 'im out of here!" at a large rally --  there are two issues, deeply rooted and increasingly intertwined. They cover America like Southern kudzu, long ancient vines, strangling the green shoots of progress, so thick that they obscure the rich land underneath.

They are America's original sins: Slavery and guns...and they have never been washed clean.

But within the new nation, fears of an all-out slave revolt only grew as the population of black people in bondage eventually swelled to 4 million. It is here that the second vine starts growing: The American romance with gun culture. Remember the 2nd Amendment, which establishes the right to bear arms in the guise of "a well-regulated militia"? By the time that amendment was drafted into the Bill of Rights in 1789, militias in states such as Georgia that were essentially slave patrols  with the goal of putting down any blacks who dared seek their freedom. By the 1840s, American traditions such as the "open carry" of firearms for personal protection were established and strengthened in the Southern slave-owning states. Wrote The Atlantic recently: "As early as 1840, antebellum historian Richard Hildreth observed that violence was frequently employed in the South both to subordinate slaves and to intimidate abolitionists."

Then came the Civil War, the Emancipation Proclamation, the 14th Amendment, and we all lived happily ever after. Actually...no. As I mentioned here recently, invest two hours of your time at your local cinema to watch The Free State of Jones, which portrays how terror against freed blacks was launched in the South with virtually no gap  after the war -- white men trading their gray Confederate caps for the white hoods of the Klan. In the era known as Jim Crow, African-Americans were kept in various forms of servitude in sharecropper shacks, denied the right to vote or to use the same facilities as whites and sent to vastly inferior public schools. You can debate whether this was slavery by another name. But no one can deny this was a shockingly inhuman treatment of an entire race or people.

So what does any of this have to do with us today? In my lifetime and during the lifetimes of most of you reading this, it's been one step up and one step back for America's deep racial wounds. Just as we glorify the Civil War, today we celebrate the civil rights gains won by Dr. Martin Luther King and the end of segregation in the South during the 1960s. But just as we ignore the horrors of the post-Reconstruction South, we also forget that the reaction to the civil rights era -- especially when many American cities erupted into full-scale revolt -- had arguably a greater impact on how we live today. Those uprisings led directly to the "law-and-order" administrations of Richard Nixon and Ronald Reagan and to "white flight" that left urban neighborhoods devoid of services, and created separate and unequal school districts.

The two most important developments were this: A draconian "war on drugs" that targeted urban drug use (while ignoring, largely, illegal recreational drugs in the suburbs); this in turn paved the way for stepped-up police activity and then so-called "broken windows" policing that led to the unprecedented and shocking mass incarceration of blacks -- the New Jim Crow. And it inspired a more fractured, more anxious and more violent American society where the use of guns exploded -- this time among whites and blacks alike. It was in the aftermath of 1960s racial unrest that the National Rifle Association went from a sensible, moderate voice for sportsmen to become the lobbying group for lucrative merchants of death that peddled fear and promised manhood until, remarkably, there were more guns in the United States than people.

It's not really that hard to see how the "slave patrols" of the 1800s too often morphed into the "stop-and-frisk" programs of the early 21st Century, or that white men worshiped open-carry laws in 1840 for pretty much the same reason that such laws are celebrated today. But the consequences are increasingly hard to ignore. The plethora of guns cuts every which way: Police in the United States are more likely than their counterparts in other nations to be killed by a civilian with a gun. That in turn makes police more suspicious and more anxious in traffic stops, which leads to hasty quick and sometimes fatal decisions -- too often when the suspect is black, even when, in far too many occasions, the suspect was unarmed.

Think again about the tragic events of the last week -- in the grim context of America's history. Think about how both Alton Sterling and Philando Castile felt it was necessary to own a gun to protect themselves in such a violent nation -- instead setting the stage for tragedy when each man encountered the police. Then think about how Castile -- a working man with a responsible job caring for children in a school cafeteria -- was pulled over and cited a remarkable 52 times by the police. Was Castile not the world's greatest driver? Probably. Was he profiled and harassed because he was black? If so, it would fit the pattern of so many formerly middle-class towns that balance their budget by fining and harassing their citizens, especially non-whites. Is this not, again, our kinder, gentler "slave patrols"?

Think about how easy it was for the delusional mass killers in Orlando and Dallas to get high-powered weaponry. Then think about the shock in England -- a nation with relatively few firearms -- that a madman across the water was able to fire the bullets that killed a member of their Parliament, Jo Cox. We don't know for sure, but some people believe the killer made a homemade gun, with instructions he received by mail from -- wait for it -- the United States, the gun-culture capital of the free world.

That's the thing about America and gun violence. With 300 million guns in circulation, there's no way to put this evil genie -- some two long centuries in the making -- back in that bottle. We can tinker around the edges and ban high-powered magazines and certain military-style weapons and better regulate sales and background checks...and we most certainly should. But it won't reverse our history, which brings us to the much deeper stain of slavery and its aftermath on the national psyche.

The roots are deep and complex. I think about my own family. I'm proud of my immediate ancestors -- educators and writers and union men from the Midwest who moved upward into the middle class during the 20th Century and then helped some others do the same. But go back to the 19th Century and -- I'm sad, embarrassed and sorry to say -- a few of my ancestors in Arkansas and Missouri fought for the Confederacy. But like I said, it's complicated. One of these rebels -- a well-known Arkansas legislator of his day named Bradley Bunch -- is also a forerunner of America's first black president, Barack Obama. (Yes, Obama is presumably my distant cousin...explains a lot, right?) It all goes to show that -- no matter what you think -- all Americans have some skin, literally, in this game.

So here's what I've been thinking in recent days -- after watching the horrific videos of the killings of Alton Sterling and Philando Castile and seeing that nightmare that followed in Dallas. It is time -- well past time, let's be honest -- for the United States to formally apologize for slavery. It's a dramatic act that could bring people together and remind everybody of the stakes -- and it's so long overdue.

And why should it be so hard? As Timothy Egan noted in the New York Times last year, other nations like South Africa, Germany and Great Britain and even the Vatican have apologized for their past sins, with positive results. But here, the only action was a non-binding resolution that passed Congress in 2009 and that seemed more concerned with making crystal clear that no financial reparations came with it.

Yes, an apology would just be the first step towards the things that are really needed -- an end to mass incarceration, the death penalty, and the war on drugs, policing that treats urban communities with respect, fair funding for inner-city schools. And it can't bring back Alton or Philando or others who have died unjustly But morally, it would be the biggest step, and the most meaningful. It would say that it's time for a 400-year cycle of violence, hatred and injustice to wind down. I'm ashamed that the Confederacy is a part of my history, and all of America should be not just ashamed but apologetic for slavery, not to mention Jim Crow and everything else that followed.

The tragedies of 2016 make it essential that we need to go above and beyond what's been done before. We need, as a nation, to take this next step. We need to say that we're sorry.