The Mexico-American border is the most heavily crossed border in the world, both legally and illegally. The history of "the wall" or fence goes like this:
- 1937 under FDR with the Organ Pipe National Park (ORPI) building cattle fences to prevent Mexican cattle from overgrazing on American land
- 1951 President’s Commission on Migratory Labor to address the "Wetback" problem. It can be summed up that during WWII, instead of recruiting American workers from Hawaii, Puerto Rico and other places that needed work, Democrats created a program to recruit from Mexico and teaching them to come up here and work and send their money home. A few years later, we had half a million illegal aliens, and the mess had been created. They did a study on the problem and what to do about it -- and recommended all sorts of things, but Democrats refused to implement those suggestions. 
- 1960's and the "War on Drugs" started the creation of a barrier in earnest, and was expanded under Nixon in the early 1970's.
- 1986 Immigration Reform and Control Act (IRCA or Simpson–Mazzoli Bill) responded to rising illegal immigration problem by providing one-time-amnesty for 350,000 illegal immigrants (to offset fears of a lack of farm workers if there was an immediate crackdown), in return for increased border security (the promise of the fence by Democrats), decreasing illegal immigration, and penalties for companies "knowingly" hiring illegal immigrants. A couple decades later, Democrats had repeatedly broken their promise to help secure the border (and obstructed it), illegal immigration had over doubled, Simpson and Mazzoli both admitted regrets for it's failures (caused by Democrats undermining it), and and the 350K amnesty was actually 3 Million (about 1/6th of the adult male population of rural Mexico, using phony documents), and is called the greatest immigration fraud in American history. It showed what happens when you trust Democrats.
- 1994 NAFTA harmed Mexico previously protectionist agriculture with cheaper American produce, this (along with a booming dot-com economy) caused a big immigration wave north, and increased the pressure on better immigration controls.
- 1996 Bill Clinton's State of the Union address promises, "One of these areas is the problem of illegal immigration. After years of neglect, this administration has taken a strong stand to stiffen the protection of our borders." to finally live up to to the promises of 1986
- 2003 Israel's first major segment of the West Bank barrier is completed (this was started in 1992), the effect is an immediate reduction in violence and suicide bombings. Each new segment sees further decreases, and this invigorates American politicians aware of the problem, to follow Israel's lead. Are they all racists? 
- 2006, After 9/11 Congress authorized the Secure Fence Act, under the guise of national security: a multi-billion dollar plan to build hundreds of miles of fencing along the border. Hillary Clinton speaks out in favor of the wall. She tried to walk that back after the Trump issue by claiming she was "for a fence, but against a wall", completely Clinton'ing the topic. Yeah, a fence is less racist than a wall.
- 2007 After the 2006 election brought them wins, the Democrats start walking back their promises, delay many parts of the project, start pushing for more "environmental studies", and by 2010 put a freeze on the project, due to cost overruns partly caused by their shifting requirements, delays and studies. Inn the end while $50B was allowed, the Democrats were able to make sure the $2B that eventually got to border security was wholly ineffective -- causing the fight we have today. 
- 2014 ISIS and Al Queda are sending people to Mexico with the intent of them crossing the border and infiltrating the U.S. illegally. A few are caught in the U.S., but in immigrations usual catch and release program, they are released in U.S. before identified, and they disappeared.
- 2019.01.09 Obama's Border Patrol Chief: Democrats talk of a "manufactured" crisis misleads the public -- the crisis is NOT manufactured. 127 agents have died defending the border. 
Reagan - We have a border crisis
Bush Sr. - We have a border crisis
Clinton - We have a border crisis
Bush Jr - We have a border crisis
Obama - We have a border crisis
Press - We have a border crisis
Trump - Let's build a wall and solve the border crisis
Press - OMG! Trump Manufactured this border crisis!
Where we sit today is 580 miles of the 1,954-mile border with Mexico has some sort of official fence. (There are other tracts which may have something like cattle fencing / barbed wire, but are local ranchers fences, not official border control). Around 400 people die per year trying to cross the border illegally, but it fluctuates dramatically depending on the economy. There are a few overlapping issues : immigration laws, national security, and broken promises.
Republicans feel the Democrats have been promising then obstructing their side of the agreement -- because Democrats win key votes with the help of illegal aliens (lookup my old haunt, the 46th district and Bob Dornan / Loretta Sanchez as an example), and Democrats see it as a wedge issue where they can play both sides. They tell the Unions and Americans they'll fix it, tell latino's they're against it, and calls anyone that tries to fulfill their promises a racist. It's win-win for them.
Progress is harder because of past broken promises by the Democrats, and their demagoguing. This is like when the Democrats torpedo'ing Bush's immigration reform by calling it amnesty, (turning his party against it), while selling the Latinos that the failure was all because of the Republicans. Or like Obama's unconstitutional executive overreach (he's been ruled against many times by federal judges and Supreme Court), or lies that ACA wouldn't cover illegal aliens (but does), that causes political backlash against amnesty and illegal aliens, then they use that backlash to paint the Republicans as racist, for this political fight.
But if the wall / border fence is racist, then all the Democrats that supported it, including Hillary Clinton, are racists as well. No one should get it both ways: to get to accuse the other side of being evil for doing what their side advocated as well.
There's a common argument that if the Wall won’t stop all illegals, we shouldn’t stop any of them. Under that reasoning, we shouldn’t arrest any rapists or murderers, because we can’t convict all of them. Emotions above reason make people silly.
People can tunnel, cut and get over/around the wall. But that doesn't mean you shouldn't have the Wall. It means you should arrest the people that would break our security. Like all barriers, it alone can't be effective -- but it is required to be part of a broader security plan.
The facts are that while many or even most illegals, are first timers that just came on a vacation and overstayed. I don’t really care about them. Once they’re arrested and deported, they can’t come in legally through the border, and they have to use coyotes or the desert path. So the bad hombre’s use the fence path — and the wall works against them (and raises their costs). As well as drug smuggling and human trafficking. So the wall may not be effective against ALL illegal immigration, or even most -- but it stops the worst elements first. So it's not a cure, but it is an aid in a cure. Those saying otherwise are too ignorant/dishonest to discuss this topic with.
If you had a miserable disease, would you take medicine that doesn't end the disease, but helps with the worst symptoms? That's what the Wall does.
Nancy is sort of the ass-hatted megaphone for partisan polarization on everything (including "The Wall"). She claimed that walls are immoral (as did Obama and others), that's why they have them around all their houses. So activists jumped the walls on one of her compounds with some illegal Guatemalans, with pictures of Americans that died at the hands of illegal aliens. It turns out while walls are immoral, sicking the authorities on them wasn't. So much for sanctuary laws. I guess that only applies to the proles, not the ruling class. 
The ACLU didn't file lawsuit after any of the last 58 National Emergencies (even Executive Order 9066: the Japanese Internment). Most of them have far less justification than Trump's border one. But to signal virtue, grab headlines, and show their new far left extremism, they are filing suit against national sovereignty and defending our borders. I don't see why they think they have any standing in this case, which might be why the shit-tweet doesn't seem to be backed up by an actual lawsuit. more...
Meme's are not for furthering communication or understanding, just humorous barbs that may have a fair point (or just be cheap shots). Here are the ones around the Border Wall fight. more...
- Organ Pipe National Park (ORPI) cattle fence: https://organpipehistory.com/border/history-of-th-border-fence/
- 1951 Wetback Commission:
- Wetback Problem:
- IRCA 1986:
- In the Strawberry Fields by Eric Schlosser, Atlantic Monthly, v276 n5 p80-108 Nov 1995
- Bill Clinton's SOTU address on border security: http://www.realclearpolitics.com/video/2016/05/17/1996_flashback_bill_clinton_talks_like_trump_on_immigration_we_are_a_nation_of_laws.html
- Israel's West Bank barrier works: https://en.wikipedia.org/wiki/Israeli_West_Bank_barrier
- Hillary Clinton on the Wall: http://www.weeklystandard.com/hillary-i-voted-for-border-fence-to-keep-out-illegal-immigrants/article/1061753
- Video of Journalist who talked to people of all ethnicities about the Wall, and found out virtually everyone close to the border wants it. https://www.facebook.com/WesternJournalism/videos/10154418883368984/
- Nancy: https://dailycaller.com/2019/01/14/activists-pelosi-mansion-wall/?fbclid=IwAR00xSpW7D09GZlqnjlsSDXk8uxmpYVVcrhYNnYs-cZFFIqvr3TUsMm4AX8