You have a civil right to allow people to illegally cross the Mexican border?
Closing the border means that Trump would take away your civil right to leave the USA through the border. If you are OK with that, you have already drunk the kool-Aid, and there is no hope for you.
Don't be stupid. Closing the border means not allowing anything or anyone in from Mexico, not preventing Americans from traveling.
So, you define a "closed door" as a door that as a door that is closed coming in, and open going out, and you are calling me stupid? And even if that were possible, you believe that it would not be a loss of an American's civil rights to be denied reentry into the USA after visiting his relatives in Mexico? You haven't given this much thought have you?
lol If Americans want to return from Mexico, I'm sure some arrangement can be made, but keep in mind the purpose is to prevent anything Mexican from entering America so Americans will lose no more civil rights that they do when they are caught in a traffic jam. Let me help you out with your whining. The real objection is that it will hurt the US economy short term, but it will destroy the Mexican economy so once the border was shut down, like it or not, Mexico will have to comply with our demands. In fact, we have already had a taste of it when Trump transferred border patrol agents away from ports of entry and while traffic to Mexico moved along normally there was a shortage of agents to check traffic coming into the US and Obrador quickly changed his mind and began helping to keep the Mexican side of the border free from illegals. Because of the President's threat of closing the border and the slowdown he engineered, the Mexicans are now working with us, and you didn't lose any civil rights.
So, you are not concerned about the civil rights of American citizens who wish to visit their relatives in Mexico, and risk not being able to return, because Trump "closed the border" (his words). As for the second half of your post, the republican governor of my state, AZ, has pleaded with Trump not to "close the border" because the damage to the AZ economy would be in the neighborhood of $4 billion per day. The mayor of Nogales, AZ, the largest border portal in the state, did as well. The Auoto assembly plants across the USA, with their "just in time" parts inventory system, would be shut down within 3 weeks. There would be virtually no fresh vegetables in grocery stores until the imperial Valley and Rio Grande valley harvests are in this summer, and Mexico would simply continue to trade with China. Neither you, nor Trump, have the slightest idea how today's world economy works.