At Large : One way to look at it
Americans are hardly perfect in our adherence to the principles on which the nation was founded. We were, after all, discourteous and ungrateful rebels at the very creation, willing to shed our blood and the blood of our former British BFFs, in idealistic pursuit of principles never before set out so unreservedly as the only true basis of political organization. All men are created equal, Jefferson said. And, all are endowed by their creator (not the king or the lord) with certain unalienable rights. That these rights include life, liberty, and the pursuit of happiness. And, that it is to secure these rights that governments are formed by the people who consent to be governed with these principles in mind.
It became a nation based upon an idea, a few ideas really. It has not become a United Nations, whose organizing principle is superficially embraced by all but severally disregarded by many; not a European Union, whose organization is motivated by economics and the need to offset the power and authority of the United States, nothing more; not a China or a Saudi Arabia or an Iran, organized around whatever oppressive principles the powerful few enshrine.
The organizing principles of the United States spring from whatever a human being is. The rights inhere with the first drawn breath, perhaps sooner in the view of some, and it is true of humans wherever they are born, although most of our global neighbors do not and will not experience life as free as we know it. Native-born citizens, naturalized citizens, immigrants, refugees, all races, creeds, and ethnic groups, one hopes, shed their tribalism and territorialism upon arrival and, coming ultimately to understand and believe the ideas embodied in the Declaration of Independence, they accept that each human one of them belongs individually to the idea that is the United States.
It is sadly true that, as a young nation, writing the Constitution by which we would require government to restrain itself, we immediately compromised and abused the principles under which we had gathered. For the purpose of this essay, I mean the Constitution's veiled protections for slavery, which survived until the Civil War and the Thirteenth Amendment settled the matter for good and for all.
But, a phrase in the preamble to the Constitution reminds us that the Founders, politicians all, harbored few illusions. They understood that the new nation was not perfect and might never be, but with luck, freedom, and the inherent goodness of mankind, it might in time improve. Thus, the phrase "in order to form a more perfect union." That is after all what we are Americans are constantly about. Thus too, the Thirteenth Amendment, the Fourteenth Amendment, the Fifteenth Amendment, the Nineteenth Amendment, and the Civil Rights Act. We're doing better, or at least we want to do better, all the time.
That's why most learned observers agree that Americans of all races get along so much better now than their ancestors did 150 years ago, or even 50. That's why Sgt. James Crowley of the Cambridge Police Department teaches a course to police recruits of all racial and ethnic backgrounds, who need to learn how to do their jobs in circumstances, very common these days, in which they come in contact with persons of all racial and ethnic backgrounds. Americans, including police, have learned to do better, and we pass the learning on.