Because as Bill Maher said Americans are number one at thinking we're number one. This is true even in light of the evidence that proves we are NOT.

Not all Americans are flag-waving, gun-loving buffons. Hillary Clinton won over three million votes than the Orange Cheeto. There's a Blue Wave coming.

Vote Republicans out of office!

I am an American and a veteran and have never owned a flag. I have never thought flying the flag makes you a patriot.

Of course not every house has a flag in the front, but there are more than I'm personally comfortable with; to me it smacks of rabid nationalism, which is almost like a mental illness. I get maybe wanting to express your love of country on major national holidays, like 4th of July or Veteran's Day, etc., but the all day everyday displaying is the mark of zealotry, imo. The rest of it, the clothing, etc., is mostly marketing bullshit and solely commercialization.

What I don't get, and I don't know if others are seeing in their areas/states, is these new flags that are patterned on the Stars and Stripes, but are different colors, like shades of blue, or black and gray. WTF is up with that? Quite often they are attached in the beds of pickup trucks, and stream gloriously along like some perverted proclamation of parochial patriotism. Can anyone explain those to me?

Well, probably for the same reason all Canadians drink maple syrup throughout the day.

Reasons vary. Self-aggrandizement is one. Hyper-insecurity is another. Or simply national pride. Or "the way I was raised" (Dad had a flag so I'll have a flag).
I don't have one at my home but I think I know a little about the mentality here.

As a Canadian I always found this in your face patriotism rather weird when I was living in the States, maybe because we are more low key about our patriotism in Canada.

As far as I can see, it's the blue collar, GOP, religious rednecks who do this, and often they also display a Confederate flag as well, as treasonous as that is.

They are commonly known to like fishin' and huntin' and often live in trailers in rural counties, and do work as mechanics, plumbers, construction.

These people are Trump's "base," since their churches equate politics, religion, and patriotism. They have been trained since babyhood to check their brains at the church door and obey older white men, as the voice of god.

It's a subset of the US population that is flag rabid. In my area, largely lower income, rural, right voting folks are the most likely to do so.

My public elementary school, circa 1972, taught us to practically worship the US flag. We greatly feared becoming THAT kid who let the flag get wet or touch the ground as there would have been a very public flag burning ceremony as a result.

Oddly, my modern age flag crazy neighbors show the flag minimal respect at best, flying it at night, in the rain, flying it bleached and tattered, but they get to point their fingers at others for not respecting it properly. Go figure.

Don't even get me started on flying the confederate flag. I see about one of those for every 2-3 US flags.

Tribalism, connectivity, solidarity, sociability, and a human fundamental need to be part of something bigger than they are alone; they all play a part. And as a Canadian, I know many up here are also not immune from such needs. Especially the ex-brits who are in great supply around Victoria where i lived for 30 years. Lol

One thing the US governments inspire which we don't however, is a love for empire building, which requires money and commitment, and the support of the population. Motivating such support is called propaganda, which includes as much flag waving as possible. Check out other empires and wanna-be empires to see many of the same dynamics. Like military parades. Lol

This, and especially @Kodaksmom's reply, got me thinking. Not so long ago, the UK was a nation of flag-wavers too, and the Union flag and a portrait of the king or queen of the time could be found in most houses. It's notable that this was most common during the era in which Britain's empire reached its peak and then, gradually, fell apart, and is now very rare - which suggests a link between the declining prevalence of the display of flags and other national symbols and the population's transition from genuinely believing Britain was the best country in the world to hoping that maybe we could be again if we kept telling ourselves we really were, and finally to acceptance that we're not actually very important on the world stage any longer.

The prevalence of flag-waving and display of national symbols in the USA seems to be following a similar pattern. The US empire rose after the British empire (indeed, the Second World War could be seen as the point at which Britain handed over the title of Most Important Nation to the US) and reached a peak in the 1950s and 1960s when Americans really believed their country was the best in the world. US supremacy gives every indication of being in decline now, and so just as was the case in Britain the flags are being waved more and the dial has been turned up on the patriotic rhetoric as the nation tries to convince itself that the golden age is not yet over. The rhetoric and deep desire to not accept that America's current problems are probably permanent, rather than merely a short down-turn, also explains how Trump became president - the majority of Americans are more than intelligent enough to see through his lies and realise neither he nor anyone else can Make America Great Again, but they voted for him anyway out of desperation, hoping that maybe he really could bring the good times back.

In the coming decades, as nations such as China and (probably) Brazil (and, perhaps even more relevant, the new breed of stateless mega-rich oligarchs) become richer and richer, gain more worldwide political power and eventually eclipse the USA just as the USA eclipsed Britain, I suspect Americans will gradually come to accept their new place in the world and will stop flying the flag quite so much as now.

I actually used to have an inverted US flag hanging in my bedroom, not sure if that counts or not.

Its because people buy flags, clothing and any merchandise with the red, white and blue since 9-11.

all?

Canada is in America

It is a stereotype perpetuated by ignorance. We don't "all fly American flags outside of [our] houses, wear stars and stripes and even display the flag anywhere and everywhere [we] can." Not even close! Yes, there are those who do that, Just like there are Canadians who act like Bob and Doug McKenzie. Bob and Doug's behaviors are certainly not representative of "all" Canadians, though the stereotype they represent probably rings true in some circles like the flag thing does here.

I have seen plenty of maple leaves, on flags, porch banners, etc. While traveling in Quebec!

this is interesting! I found the rule and etiquette to fly the US flag here:
[usa.gov]
but if you want to download the pdf file it is located at a site owned by Amazon (amazonaws.com).
[app_usa_prod_eqffnyamdzrb.s3.amazonaws.com]

As the "tall kid" I was the American Flag carrier on two different color guards, and I had to learn all the rules about displaying the flag. Displaying "flag images" is traditional in many countries I've seen. Wearing a flag pin is really only appropriate in a multinational meeting or event. I have a "flag image" on my briefcase for "liberal" political purposes; I want people to see that cycling is a "patriotic" means of transportation. I used to put flag decals on all of my bikes, since they cross borders from time to time, but I gave up when the Chinese-made decal sets didn't come with starboard-side flags. Any house on a shore (ocean/gulf/great lakes) is more or less required to fly a flag, but that's never enforced. Flying a flag from your car without replacing it when it inevitably gets ragged is a no-no. I think it's an error on the part of the left to not do liberal activities without flags or flag images; after all, the U.S. is the very definition of what a Liberal Democracy is. Usually.

For the freedom it represents. I love my country even if its in a rut right now. Opportunity is all around us here. You can be all you want to be. I trudged sometimes and had it easy. It all came together and im retired. Ive seen other countries and i always want to come back to America.

I got to agree, there are no English flags hanging here

America ?? the least said the better !