Immigration only really causes economic issues with bullshit employee specific visas like H1Bs - those visas trap immigrants in powerless positions where they're unable to advocate for fair compensation and drive down overall wages.
Mostly to avoid having infrastructure and social safety networks overwhelmed. Yes, you will also see wages be depressed by large-scale immigration, but that's something that could--in theory--be controlled by strengthening unions and labor regulations. That's not where we are though; right now, unions and labor regulations are fairly weak, and are being gutted by courts even as the NLRB tries to strengthen them.
Housing takes time to build, and good city planning is necessary to ensure that cities are sustainable rather than being sprawls. (Not many cities do that, BTW; it's usually, "oh, we'll just add another lane to the existing 20 lane interstate"). Given that we're currently in a situation where there's insufficient low- and middle-income high density housing, and few companies are willing to build any more, competition for most of the immigrants that we're seeing--people that are trying to get away from deep economic woes--would be fierce for housing.
There's also the carrying capacity of the area they're emigrating to. Housing in particular is one aspect of it that's already very very tight in most of the Western world. Even without immigration per se, this problem plays out every time a major company moves headquarters to a new city/state. Lots of new people, and a very slow to respond housing stock means surging prices. Schools and other social services also get stretched - but they're much quicker to respond to the demand.
Immigrants often are expected to work for less money. After all, they usually immigrate from an economically worse country, so they don't expect to land top tier wages.
You keep filling in minimum wage jobs with an endless supply of immigrants, then there is never a worker shortage and never any incentive to raise the bar. No company needs to compete with higher wages to attract talent. In fact, it can make things worse and cause a race to the bottom... Reducing wages on existing positions until workers quit and just filling it with less skilled workers.
Immigrants are often effectively scabs. They work for less, take more abuse, that sort of thing. And It's a lot harder to form a union when half the workers don't even speak the same language.
There only are so many resources for them. Here in many European countries the main issue (I think) is that with the current numbers we fail to teach them all our language (it's simply not possible without having more language teachers available, and apart from needing those teachers that also needs more money). Without knowing the language their professional development is massively hindered, causing many to remain lower class, and causing disproportionately high crime rates among certain groups.
This leads to further problems: In the big cities there already are schools where people who speak the local language are a minority (for example in a primary school near me they have two classes for each grade (1-4) for children who can't speak German yet and one class for all grades together for German speaking children).
So guess what people do: They go to a district with less immigrants, while the districts with many immigrants keep getting more immigrants (since cost of living is low there and as pointed out earlier many struggle to leave lower class). We're re-creating segregation. This makes it even harder for those people to leave lower class, since they have no networking opportunities but only know others from lower class instead.
Even the left wing parties are now saying that we have to reduce immigration and instead integrate immigrants better.
How quickly your culture can absorb new people. If you've got a hundred people who are in culture a, and you integrate 100 people from culture b. Now culture a is 50/50. And it's hard for culture a to maintain its traditional positioning.
If you want to maintain a culture, a people, a language, you need to gate how many people enter the population at any time. So that it can be absorbed.
You similar problems with militaries, how quickly they can ramp up new recruits will still maintaining their previous cadre culture.
It depends on the kind of immigrant. You have students, high educated workforce, people that flee from war/not safe to stay country and people that just want a (economic) better life.
I think too much of any immigration can cause maybe an issue that the majority of people are new and that the culture (how do we interact with each other, what is acceptable behavior etc) has not settled.
It’s easier for most people to believe that different coloured or dressed folk, or those that look the same but speak differently, are the reason your life is difficult. It couldn’t possibly be the people that look and sound like you that are your problem. In the UK it’s been said before that a white British guy in a factory job has more in common with a Jamaican bricklayer or a Polish chamber maid than they do with Boris Johnson. I believe that position.
The "shot in the foot" effect when you accept immigrants from conservative/racist countries and they and - most likely - the next generation will vote right wing which more accurately mirrors those conservative/racist beliefs.
Historically, US actually was quite welcoming of immigration, including from Mexico. It tends to ebb and flow. I was taught by an economist that typically you open the flood gates when you want the labor, while restricting it when you don't. To him, labor works just like goods in supply/demand curves. Flooding a market can drive down value of labor, etc., which can be bad for local workers. Obviously it's a little more complex, but that's the jist.
The trouble is, with globalization, one must wonder if that S/D curve is still valid. I imagine it is in some sectors, but in others, those jobs have been outsourced. If this is a bigger strain on demand, then it's better to keep immigration on lock. That would at least help explain why it's so hostile currently, but I'm just thinking out loud. I don't necessarily agree with the economist approach.
From an economic perspective, it's mostly positive. Raising a child is expensive, and those costs go on for about 20 years before you have a person that's economically productive. Most Immigrants are adults and can join the workforce immediately. The economic costs of their childhood was paid by the country they came from. It's a negative for the country they came from, this is refereed to as a "brain drain." But for their new country, it's like a tax paying worker just appeared out of nowhere.
As for the economic negatives, the big one is housing. Too much immigration all at once can result in a shortage of housing. It can also put stress on public services and infrastructure. Businesses may not have the capacity to serve a larger population. These things can adapt of course, but you can't instantly build a house and you can't instantly expand public services, etc. So you might want to limit immigration so an area can adapt to all of the various economic needs of a larger population. An immigrant will work and pay taxes and contribute to the local economy, so long term it's all positives, but there can be a lot of short term problems if a population grows to rapidly.
As for social... well I'm not really much of a sociologist, but just from I can see, people who already live in an area might be uncomfortable being around people of a different culture. Might say crazy things like "They're eating the dogs!" Yeah that's crazy, but it is a problem. Not caused by the immigrants themselves, but it's a problem that does happen when there's immigration.
But there's social benefits. Can learn from a new culture. May get some new options for restaurants to go to.
Generally the young will enjoy more social benefit (going out to the different restaurants and learning about different cultures), but the older people will tend to be uncomfortable with it. But that's just the tendency.
So overall I'd say you do need limits on immigration to mitigate the short term issues, but it's all positives in the long term.
In my opinion, country-based immigration paired with needs-based works really well.
Ultimately, many of the best parts of the culture of a place are because of what people brought with them years ago. Some of the best restaurants are because someone in India moved to the UK, and then moved to the US and brought the culture of Curry Mile or Brick Lane with them, or because a community of Greek railroad workers decided to set up bakeries using their known recipes that all the locals love.
The same often goes for business. Look at the rise of Aldi and Lidl, and how cheap produce and great workers rights will suddenly make local supermarkets look in bewilderment at how markets they once dominated are being torn away from them.
IMO, if you have skills to offer, you should be welcome. I'm currently in the process of moving to the US on a high-skilled visa, and it is mad how one country will require thousands in legal fees and 24+ month waits while a country next door will say "Shit, you can teach?! Come join us! If you want to stay permanently that's fine!"
When multiple cultures mix together, one of two things can happen:
The cultures mesh well and either coexist or mutually mix into something new
The cultures do not mesh well and this leads to all sorts of problems, especially increased crime
The second usually happens when both cultures place opposite value in something. For example, one culture places a high value on self and the other places a high value on being in a group, this can lead to a divide between cultures. Eventually, the resentment each group has for each other will lead to violence and other sorts of crime. One culture may think "I made the money for myself," while the other thinks ,"we should all share the money." If people don't learn how to get along, you can probably see how that would increase criminal activity. In most cases, it is usually the expectation that the immigrant adapt to the culture of the new place they have moved to, rather than the new place's home residents being expected to adapt to every immigrants different country cultures.
It also isn't good when immigrants enter a new country and do not know the laws of the country they have entered. They may commit crimes that could have been legal wherever they came from, but now someone may be a victim to a crime and the immigrant did not know. Now, usually immigrants that legally enter a country do learn about the basic laws of the country and the basic culture, but ones that enter a country illegally may know nothing about the place they are in. They may continue to act the same as they did in their previous home, which may have very different laws, leading to further divide.
Immigration in excess and esspecially in combination with exploititive or unenforced labour laws and mismanagement of other resources and infrastructure, can decrease wages, and cause shortage of key resources. For example, if there is no new housing being built, but there is very high immigration levels, housing prices will rise, and availability will be limited.
Housing, job availability and potential erasure of culture. I think it depends on what migrants you let in though. Also some groups forming bubbles and refusing to integrate as well.
Personally though, I think kids watching american media on their mum's ipads is a greater risk to our culture than Mohammed and his family down the street
Also, some immigrants are more racist than white people. Which is sometimes kind of funny. Although my white friend got beat up in Bradford, so sometimes it isn't.
just have a look at the EU and also Germany with some crazies wanting shariah law...this is Germany we are talking about,with their histories and what not
It's a complex and polarising issue. The main problem is that some, sometimes most, of immigrants don't want to assimilate. They are creating ghettos, don't respect local laws. Other issue is that governments prefer to spend tax payer money for accommodating immigrants instead of solving nation's issues.
I wouldn't limit immigration per se. I would limit unchecked illegal immigration and spend more money on assimilating immigrants that want to contribute to a country they moved into.
It depends a bit on how you define immigration. Is what the Spaniards and English did to the Americas immigration or something else?
If the influx of a different culture is so big that it displaces you and your children like it did to the Native Americans, then I understand that you'd want to stop it.
If you provide real social security for anyone in the country and don't limit immigration at all, you attract people who aren't willing or able to work and want to live off social security.
Many people believe that too much immigration causes the destruction of a nation or of an ethnic group by means such as the disintegration of its political and social institutions, of its culture, language, national feelings, religion, and its economic existence.
There is no or a very small impact of regulation on the number of exiled people coming in country.
However, making more people illegal let bosses exploit them more. Those workers could not sue their boss because of those regulations, and most conservative unions rely unfortunately too much on legal solutions.
So if a country couldn't limit immigrations, it could exploit more people and bybass human right with regulations against exiled people.
Yes, this is only positive for far-right bosses, and awful for others. But guess who decide in a capitalist economy ?
If immigration leads to more unemployment, then that is an economic problem, especially in the hypothetical case where the social benefits system is getting more and more strained by an influx of unemployed people. But generally, I think that you can expect that the immigrants will soon find employment. Besides that, there's the cultural aspect that @jet@hackertalks.com mentioned. You could also make the point that the country's infrastructure is more and more stressed as the population grows, but that is fixable and potentially counteracted by the labour potential of the immigrants themselves (i.e., qualified immigrant work forces can make a large-scale infrastructure overhaul possible that will lead to greater national capacities and a net benefit for the entire population).
Aside from these things, I would argue that most of the other reasons boil down to xenophobia or racism.
Infrastructure is a large issue. Border towns can become saturated, which will reduce living conditions, and when immigrants move to larger cities, they can often have trouble finding places to live. A lot of this can be because of a communication barrier. Sometimes that is because there are too few to translate, but there can also be educational issues. As much maligned as the US education system is, it is better than some others, and when your culture eschews school for an early start at earning a paycheck, communication in any language becomes a challenge.
Many issues can be overcome, or at least minimized, by compassionate workers, which many that work with immigrants are, but there isn't enough funding to get compassionate people where they are most needed. Supporting increased budgets at the border isn't always about putting guns on the border, it can be about improving the infrastructure that helps get people where they need to be in more efficient ways. I'm starting to ramble, though, and I think I've given a partial answer to your question.
Many companies love undocumented workers. Easy to abuse, underpay, overwork. So of course they hate it when those workers can easily get documented or citizenship. Following the law is such an annoyance. Cuts into the profit margin. That is why big business and the nationalists often work together.
The nationalists kinda know they're getting played to generate corporate profits, but they also enjoy having a target to look down on.