As much as people hate to hear the "it's complicated" answer in regards to anything regarding Israeli affairs, well, it's pretty complicated... But to name a few reasons:
Religious fundamentalism/Zionism in the United States has been forcing politicians to take sides or else alienate their constituents - Christian fundamentalism is bizarrely in favor of a Jewish state because it fulfills their own doomsday prophecy, not for any logical reasons or out of a genuine desire to help the Jewish people.
Weapons manufacturers and arms dealers are lobbying to keep Israel as a partner considering they are almost always mired in some kind of conflict. It's a multi billion dollar industry and the people who make guns, bombs, artillery shells and ammunition are not keen of giving up their cash cow.
Consider of course the historical ties and diplomatic agreements, which if flippantly broken send a message of unreliability to other allied nations (I'm not sure I totally agree with this one, as the USA is basically a schizo nation flipping back and forth once every 4-8 years between isolationism and globalism depending on which party holds office).
Lastly, since the Cold War, the USA has kept Israel close to project their own influence in the middle east. Countries like Egypt or Saudi Arabia would have to think twice about provoking the United States considering who their neighbor is. Great strategic location bordering the Mediterranean Sea that makes it easy for USA to get soldiers on the continent if it ever comes to that.
Isreal is screwed without the US. Without its backing it will turn to Russia. It's a valuable ally for the US due to it's location and intelligence services
It let's the US government waste taxpayer money on military hardware to make the billionaire class even richer. Money that would be far better spent on US taxpayers.
It panders to evangelicals, who need Israel to exist in order to fulfill their Book of Relations, End of The World, apocalyptic jerk-off fantasies.
That depends who in the government you're asking about. Every branch has their own motivation. For example, the military likes conflict happening elsewhere. Politicians want to be reelected. Racists like it when Arabs and Jews kill each other. And so on.
(Of course that's a vast simplification, but you gotta at least say who you are talking about to get a meaningful answer.)
There have been lots of ties between America and Israel and lots of people formerly living in the USA (and/or having fled there) emmigrated to Israel.
Since then the stance hasn't changed. The two countries have ties, are allied. And that's the political side. As people pointed out here there are other sides to the story... Religuous beliefs of christians etc... And obviously it's difficult to resign from a long relationship.
(Edit: Especially for a country as conservative and traditionalist as the USA. I don't see a politician getting elected for saying: 'Look, we need to rethink our old ways of doing it.' And the US is very capitalist. And selling arms is a lucrative business.)
Tl;Dr - Massive unopposed lobbying campaigns for the last couple decades and the Cold War.
Honestly? Domestic politics. Israel has had an influential lobbying arm in the US since World War 2. Combine that with post war guilt about turning Jewish refugees away during the Holocaust and the cold war position of Arabs and you have a slam dunk case for the US backing Israel until the mid 90's. Which is what you see in history.
However Bill Clinton correctly identified the political time bomb inherent to Israel after peace talks fell through and began pressuring them to end new settlements. The lobbying groups helped get George Bush elected because of that. (To be clear these are Americans, some Jewish, some not, that believe in Israel for varying reasons. Not Isreali agents or anything like that.) George Bush also did not want that political hot potato and kept Clinton's pressure going. Especially as he tried to rally support for a second war.
At this point around 2003 alarm bells started going off in the pro Isreali lobbying groups and in the Israeli government. They sensed that now that the cold war was over they would not receive special treatment anymore. So they began laying the ground work for major lobbying efforts at the city, county, state, and federal levels. They also began a pressure campaign on media to have issues presented on a light partial to Israelis. In 2004 conservative Israelis and their allies had a taste of their worst nightmare. The Israeli prime minister ordered settlements in Gaza to be abandoned. This was because of international pressure.
Netanyahu and the pro Israel lobbying groups proceeded to work at making America a shield for Israel over the next 15 years. Resulting in many states and localities passing laws to prohibit the BDS movement and define any criticism of Israel as Anti-Semitism. This is known as the IHR definition which the US House just adopted.
While there is a significant portion of the US population that supports Israel as a result of decades of cold war propaganda, they aren't why the government is so vehement about it. Israel and its friends have lobbied our government directly for nearly 20 years without much resistance. Pro Palestinian groups, and positions have been seen as largely terrorism aligned in a country that's been at war with groups labeled as terrorists for 20 years. So any resistance that was encountered was easily dismissed.
That's why our actual infrastructure of government favors Israel in places. Now why are we so actively supporting them instead of just letting the government do its thing? That comes down to one man and no one knows his reasons but him.
Other suggestions -
Christian End of The World Theology- This explains some grass roots support but not the majority of grass roots or the government's support. The US government has historically been hostile to this theology.
Oil - This doesn't track. We're in a big push to be independent of foreign oil and trying to transition to green energy. It could have been a reason 20 years ago, but not now.
Military Asset - This was true until the cold war ended. Now the US has bases all over the middle east and Turkey, a NATO ally, is emerging as a competent weapons manufacturer with far less support than we give Israel.
This is the question of the century. Maybe decades from now, there will be a book, then a movie. My only guess is that they have something dirty on our politicians. Something so egregious that they are willing to sacrifice almost everything to keep it quiet.
That seems based on statistics there are some serious breaches of racist hiring policies.
Yet why can't people talk about it? If you posted that for Irish descendants no one would have an issue complaining about their dodgy hiring procedures.
That's data driven and questions should be raised.
It amazes me that no-one ever seems to say (not that I have seen, at least)...Isreal is a western, democratic state with nuclear weapons in the middle east.
It's basically a major power base for the west in the predominantly arab part of the world.
Anything else is a side arguement as far as I'm concerned.
This is the only explanation that spans parties and ideologies. Loosing this foothold would be detrimental to regional military and diplomatic influence.
We need to trust such a country to be judicious in their use of force, to not engage in any unnecessary conflict that puts both they and their allies at risk, and we want that country to be stable and share our values.
Israel is not demonstrating these qualities, at least not now.
Well yeah but why would the US quibble over the strength of their democracy? It's a western, pseudo-democratic state with nuclear weapons in the middle east.
This isn’t flame bait. I honestly didn’t know. I’ve heard a mixture of confused ideas and wanted to see what people here thought.
Why can’t anyone here answer it? Shouldn’t it theoretically be transparent to at least some people in the US? Maybe it’s not but that sounds like a huge problem
Strangers on the internet are not qualified to answer deeply complex questions like this despite what they might think.
Foreign affairs is something that people dedicate their lives to studying and understanding. I seriously doubt those experts are here answering this question.
Do you notice how all of the answers you’ve received are inconsistent with each other?
Historically, almost any US politician who didn't give full enthusiastic support for whatever war crimes Israel wanted to commit would lose their job because of AIPAC. That doesn't seem to be true anymore but old habits die hard.
The Mideast has a bunch of oil and we like to go on little military/covert operation adventures there that coincidentally end up with leaders in place who want to sell it to us for cheap. That means it's pretty useful to have a no-questions-asked stable ally on the ground there; we have some others, but they're not as reliable or permanent or beholden to us as Israel is.
IDK if you've noticed but worldwide human rights is not a real big priority to the United States government 😢
They were our only ally in the Levant during the cold war. The other Arab states were USSR aligned. Not that they were a great ally, but political motivations at the time said we needed one.