If the US had a philosophy, what would it be?
By a philosophy, I mean less what American philosophers wrote, and more what the collective philosophy of its citizens, everyone from bankers and politicians, to the layman, is.
And what about the philosophy of the UK, Germany, France, Italy, Brazil, Russia, India, China and Japan, what would they be?
Such a National American Philosophy can only be limited to its Constitution. Currently what is prominent are those ideas of the Republican versus the Democrats. Note the 1st amendment’s Freedom of Speech is prominent.
Not related to the OP but as a side point, there are specific philosophies produced by American philosophers, e.g. the analytical [American] versus the Continental [European], the pragmatism of William James, etc.
It can’t be limited to anything else, like what young Americans tend to believe in, or educated Americans?
Right, much or most of its political philosophy is encompassed in the republicratic party and the constitution.
Noted.
But do any of these philosophies speak to the masses?
Not really.
Most philosophies have a measure of something that can be applied to the collective. But if by ‘speaks to the masses’ you mean something along the lines of Woody Guthrie’s, “This land was made for you and me”, then it’s basically about equality.
I add to Prismatic’s political observation that the current situation is one where some are promoting that this land is more mine than yours. A perception that is bound to fail simply because the economic engine of America cannot be allowed to fail. Reps and Dems will be having a Kumbayah festival before that’s allowed. And no need for me to tell you how they would deal with wrench-throwers.
But aside from all that, again, it’s about equality, cooperation and the possible yield of a better future. Go through as many current and historical presidential and candidacy speeches as you like and you’ll find those points in one variation or another.
Or are you in some way asking ‘academically’ about an existing philosophy that can be applied? If so, then what comes to mind is a kind of centrism, a balance affording an even keel. Can’t let the boat capsize in today’s waters infested with sharks domestic and foreign. 
I think it tends towards problem solving, rather then values. Instrumental reason. Pragmatism. Which is related to an ideal of classlessness. You can fix it, you get paid or get the job or the spouse or the raise…It’s not amoral, but it might appear to be to other moralities. It also ties in with individuality, the lone entrepreneur or genius. Can do.
As mentioned it is only a side point, thus not relevant to the OP.
I believe to speak of American National Philosophy is very limited. What is more relevant is American politics, culture, social, economic, arts, sports, and other activities.
While I too think America’s ethical/political philosophy is equality, among other things perhaps, at least in part, it’s a limited equality, not an absolute one.
It’s an equality at the voting booth and before the law (regardless of sex, race, creed, class, etcetera), not an equality of outcome, or even opportunity, as people born into wealth have more opportunity.
That being said, the rich can hire better lawyers, and while bribing the courts is illegal, of course it’s a practice which remains widespread, in addition to bribing politicians.
Since the early 20th century liberals have changed things, so we have a little more equality in opportunity and outcome, but not much, and we have more corporatism.
To equality you can add private property and personal autonomy, but of course there’s plenty of public property and interpersonal demonomy too.
We could say America’s ethical philosophy is also monetarism, if you will, the idea that peoples lives are improved if they sell more in the marketplace.
What you spend your money on, be it yourself (increasingly it’s on yourself), family, investments or philanthropy, health, materialism, sensuality or travel, isn’t so important as you’re making as much money as you possibly can (the more the merrier) doing whatever it is you enjoy doing and are good at.
While not everyone agrees, officially success is determined in large part by GDP growth, it’s assumed if GDP is growing, people are probably happier, healthier and so on, or GDP becomes the objective in and of itself even.
As far as epistemology goes, it’s scientism, and as far as metaphysics goes, it’s materialism.
To all that you can add technocracy, and optimism, the idea that tomorrow will be a better day collectively, and individualism, if we only have the right attitude/philosophy.
Nothing is absolute, at least not in the dimension we’re existing in. What we aim for is a working, operational equality which while being limited as you noted at least it’s better than nothing. Perhaps in the realities of time there could only be a working/operational national philosophy, something befitting the circumstances of the moment. Hmm . . that sounds like the conservative/progressive playbook. 
You can thank the Virginia Company of London and some others for that. It’s doings laid the monetary foundation for the USA. Independence may have drawn some lines but the business fix was already in.
The Declaration of Independence is pretty straightforward in presenting itself as a philosophy. “We hold these truths to be self-evident” - that phrase contains a thorough understanding of what philosophy is and must do.
On the whole Id say US is Masonic.
I think the UK’s philosophy is getting an overhaul.
I don’t think that’d resonate with most Americans, most Americans have a straightforward understanding of thought and language, that they should represent reality.
Of course, but I think if the American people and politicians voted differently, they could have substantially more equality without civilization collapsing or having to travel to the 4th or 5th dimension, or bring the 4th or 5th dimension here.
Americans insist on having equality in some social spheres, but are ambivalent or apathetic about having it in others…at least half the time, the other half politicians just don’t listen to them.
True, Americans and people in general aren’t terribly interested in philosophizing much these days, even amateurly, unprofessionally, which’s probably in part why academic philosophers have grown detached from common concerns, practical affairs, or vice versa
What about Ayn Rand?
Does her philosophy encapsulate what many or most Americans believe?
Their morals, values, attitude, approach?
Agreed, the declaration of independence is a major, if not the current in America’s political philosophy.
But what I also want to know is: what do Americans consider to be the good life?
What are we to do with all this, liberty?
And how do Americans think, how do they view the cosmos and their place in it?
Note I’m asking these questions in a more philosophical than scientific spirit.
Really?
Interesting, please elaborate.
What’s also interesting is: how progressives, libertarians and conservatives can read the declaration of independence, hear the words equality, liberty, and interpret them very differently.
Progressives hear them and think: education, healthcare, food, housing, freedom from discrimination, freedom from hate, etcetera.
Libertarians hear them and think: my right to swing my fist ends where your nose begins.
Conservatives who aren’t also libertarians hear them and think:…I’m not sure what they think.
Perhaps they think we’re forgiven by Jesus, but not necessarily by society, the state.
Or we should be punished for the sins we commit (fornication, narcotics, etcetera), not for who we are or what we believe (race, creed, etcetera).
Or we shouldn’t be punished for things that’re supposed not to harm others, but for things that’re supposed to harm others, even indirectly.
Or perhaps they think such matters should be determined municipally and at the state level rather than federally.
I have little idea, maybe they just pay lip service to the DOI.
Maybe they think: freedom from tolerance, from having to tolerate other peoples wickedness, or eccentricities.
Oh, so now you’re making it an immigration issue! 
Of course, we can’t have 4th or 5th dimensionals taking our jobs too, so we’ll just have to do without absolute(s) (equality).
Our outlook as a country seems to be under pressure and judgement on any given day, and our Government and lobbyists are constantly having to react to these daily changes we are going through because of our MPs and Honourable Lords constantly doing u-turns on so many policies and legislation in their need to keep up with our constantly-changing sociotel needs.
The previously rebranded British model seems to be reverting back to an (amended) original model, and our philosophy is constantly amending alongside that change… until a synchronicity is reached.