For very specific examples you can look towards the EU's decades long stance on immigration which resulted in the refugee crisis since (and before) 2015, as well as countless integration and immigration issues (cf Sweden, France, Italy, etc.).

The socialist and left wing coalition have consistently voted against measures to improve border security and tighten the restrictions for people wanting to enter [1]. As people have become increasingly frustrated with these policies they've increasingly voted in right wing and conservative parties (in comparison to the ruling parties) [2].

We can also look towards the UK where socialist politics have been a mainstay since the 90s, to the point where now the Prime Minister (Kier Starmer, Labour) is a self-proclaimed socialist [3]. This is of course directly tied to the waves of mass migration under Tony Blair (Labour) which also resulted in the Socialist Party splitting from Labour because he wasn't "radical enough" [4].

[1] https://theconversation.com/what-are-the-eus-new-migration-r...

[2] https://www.brookings.edu/articles/understanding-europes-tur...

[3] https://www.vice.com/en/article/keir-starmer-i-still-see-mys...

[4] https://www.socialistparty.org.uk/articles/94799/27-04-2022/...

The refugee crises are largely "Push" driven not "Pull" driven.

...and the "push" was caused by alliances of western countries destabilizing the migrants' home countries.

That "push" is pressure, and Western leftists opened the valve wide open to allow all the flow into the West.

I don’t see an Open Borders policy in any of those links. Most of them are about how the countries are tightening their rules for allowing migrants. You cannot tighten rules unless they already exist, they wouldn’t exist if the policy was Open Borders.

Invoking “socialists” over-and-over doesn’t prove anything about Open Borders and kind of undercuts your point. There’s also no mention of right-wing leaders like Ronald Reagan or George Bush. They both pushed policies that increase immigration and asylum seekers.

==We can also look towards the UK where socialist politics have been a mainstay since the 90s,==

The UK was lead by the Conservative party continuously from 2010-2024. You somehow skipped all of that and went straight from Tony Blair to Keir Starmer.

> Is there a part of the US’s 250 year history where we weren’t bringing in immigrants from poorer countries to provide cheap labor?

Pretty sure they're referring to a de facto open border policy, where you basically permit all sorts of illegal immigration and don't really enforce the laws. Accepting immigrants at Ellis island was not illegal immigration, for instance, but crossings at the southern border often have been.

== Pretty sure they're referring to a de facto open border policy,==

I’m summary, not open borders.

De facto policies are still active policies, even if they aren't de jure.

You haven't demonstrated that it is de facto policy, only asserted that it is.