Can the US borders, North and South, actually be sealed to prevent significant unauthorized crossing?

I would have fun making it difficult to cross the wall and reduce the crossing by 95%.
I enjoy lasers, that said: I would make a 100-200 foot kill zone and use 1-2 megawatt IR-cutting lasers randomized by computer to make the kill zone 6" above the ground to 5' above the wall and everything in between. Mirrors would be placed between 6" - 15" apart and set to take any of 50,000 randomized patterns.
That would be a unique deterrent.

The larger issue, which I have reason to believe is the reason for the deer-in-the-headlights look you get from politicians who get fully briefed in, is that sealing the border (assuming it could be done) would be like closing the valve on a pressure cooker without turning off the heat. The flow of people north, and money back south, is the pressure relief valve that keeps Mexico from collapsing into full failed-state anarchy. If that occurs, the cross border flow will increase ten- or hundred-fold, and they'll all be carrying Tom Kratman's 51-foot ladders. And back on their side, the national security implications for the US will dwarf everything we see today. Sealing the border today would lead us to a decades-long military incursion to impose stability and governance on Mexico tomorrow, at a prohibitive cost in blood and treasure. Didn't Harold Coyle write a novel about this years ago? His premises were sound.
Cinch down the flow with border controls, and reduce the economic incentives for heading north, with a light hand on the throttle and an unblinking watch on political and economic conditions in Mexico - that's about all we can really do. It's a classic "wicked problem" that minefields and .50s just won't solve.

They flock here because its the land of the free and home of brave. I would want to come here too. The problem is we fix things by spending more money on the same programs that havent worked. We shuffel a couple leaders beef up man power and fix nothing. Look at our vet suicide rate still 22 day. Day after day the # is actually about 40 each day. See the same programs more money shuffel people do the same thing. I have even written the white house everyday for three years with a guarantee new way to prevent suicide but one replied. We like looking like we are fixing problems. We shuffel people and put money into the same old programs. Why do we want secured boarders in the first place? I always hear the racist reply keep those no good free loading Mexicans out of here. Its just plane racist and not living through the the words of God. You know love and kindness to all. These people crawl through the desert with snakes, no water, coyote the animal and also the human type coyote. I think its amazing how hard they will work to get a taste of the freedom we have. People will always want to come here. So what do we do. Well we put all efforts into collecting taxes and back taxes. Have every illegal here right now that brings us $1500 a person or $2500 a family and recieves the proper vaccinations will receive their citizenship. Also figure out how to help make a middel class work in Mexico. I dont care how they got here but when they get here then thry need to follow our laws. Imagine that take the man power at the border and start going door to door and setting up finacel payments, verifying future taxs are being paid and maybe just maybe some of our debt will be removed and our economy may see a rejuvenation with a flood of new tax being paid. We have to one day take our hate of other human being and replace with love and kindness to all yes even the Latina coulture. We are all human being and we all desrve happiness no matter where come from. Stop spending and start collecting. We will see new life. Can you imagine crawling through just hell to get to this place of happiness to see and hear such hate. Collect what they owe and move on!

Personally I like lasers which should be used at the top of any and all walls. Obstacles is a delay to the inevitable. However, it should be more of an obstacle where the person has to REALLY want to cross over. Anyone can crawl over or under a fence, how many will figure out how to cross a 10kw laser fence that is the secondary fence. Now that would be a challenge for both the people crossing the border and the people assisting the moving of human cargo across the border.

No. Physical barriers do not stop economic pressures, they only drive up costs.

Only if we are serious about border security will it ever actually be effective or make a difference. If we decide that we want to secure/close the borders, I am sure that we could hire and train enough people to make it happen. But until the politicians decide that to be the CoA, nothing will make that happen.

The southern border is typically most often discussed, but the northern border has its problems in certain locations as well. Some sort of sealing is possible, but to be effective sufficient staffing will be required. Hadrian's Wall, the Great Wall of China, and the Israeli border barriers work because of the garrisons assigned to cover them. Drones, satellites, helicopters, sensors, and TV cameras cannot be expected to completely replace the people element.

Personally, I would pull of our Troops from the majority of our overseas bases back to the US and return the bases to their home Countries. We needed those bases during the Cold War, but now they're obsolete. Then I would "Blacken the Skies" with planes spraying weed killer over all the Afghan and Pakistan Opium Poppy fields 24/7 for about a week. Then I would stop all aid to any Country that supports any type of illegal activity toward the USA and our allies. I would tell the World that the US will no longer tolerate any terrorist threat from any country, and if terrorists are found living and training in a country, the US will attack and destroy the suspect Terrorist area where ever it is. There will be no warnings given. Iran and North Korea will cease their Nuke programs or those programs will be destroyed. If any weapons of mass destruction are used in the United States, the leaders of the country(s) of origin will be subject to swift and severe retaliation. The US Military would secure our Borders 360 degrees. Any ILLEGAL ALIEN attempting to cross the US Borders anywhere other than a Checkpoint, (thousands of these checkpoints would be established and each person crossing would be fingerprinted, photographed, and required to give a DNA sample. They would be issued a photo ID, and all the info would be placed in a centralized redundant computer databases and would be accessible to all branches of the military and all law enforcement agencies.) Anyone attempting to enter illegally would be subject to the use of deadly force. It's time for America show the World we are the most generous country to our friends and the worst nightmare to those that are not.

No. Not now, not ever.

I read all these posts and most ofthem i can agree with minus those who want to make the southern border a war zone i agree that felony charges for the companys hiring undocumented immigrants should be a major consideration factor. Hell, hey are a major contributing factor to human trafficking from the south to the north. This has been a long standing activity for MANY decades. A lot of these companys who engaged in these activities have enough money to throw at any charges brought against them though, and lobbyist in washington buying off the congress and the senate. so you see this issue is not as simple, is it? Also, lol, there are many for profit prisons that are making money on holding undocumented immigrants that are guilty of no other crimes, indefinitely to make there profit margins. Many of these prisons also have contracts with other private companys to use prison labor to produce their goods. Interestingly, government officials can buy stock from companys using prison labor (stocks do pretty well). Prisoners, and unrepresented quarter of our population, is being used as near slave labor, lol. Some of them even do tech support for private companies, and we are worried about our jobs going overseas? Also, there have been many reports that if prisoners refuse to work, they are out into solitary confinement for at least a week. Some of thse prisons look like wharehouses with holding pens, and the prisoners complain that the k-9s get treated better than them. Also, private prisons aee set up in parts of the US where there is so much economic need, and for lack of creativity, legislators will welcome private prisons to their towns. It used to be that the US would simply deport mexicans back to their country, and if they had a repeated offense than it would be prison time. This is not a federal crime actually, it is a civil crime, that states have relinquished the rights to act on themselves. Anyway, the issue is bigger than what you think it is, and i am telling you that our country, our military, monitors the southern and northern boarders like its nobodys business. I know this. So, unless you want some target practice, i reccomend you do some research. That is all i have.