I wrote my previous article from Mexico and I was hoping that I would be able to get across the border to return to the U.S.

That turned out not to be a problem. Our family successfully crossed the border and are at home in the United States.

The border was, by the agreement of the U.S. and Mexico, closed to "nonessential travel" shortly after midnight on March 21. But how tight is it?

That might depend on where you are and how you define "nonessential".

From CNN:

The Trump administration is limiting nonessential travel on the US-Mexico border and barring migrants illegally crossing the border from entering the US. Citing the "unscreened" and "unvetted" people who come into the US from the southern border, President Donald Trump said the border would be sealed off "mostly, and even beyond, but mostly during this global pandemic."

Trump administration limits nonessential travel between US and Mexico, by Priscilla Alvarez, Geneva Sands, Betsy Klein, Jennifer Hansler, CNN, March 20, 2020

“Nonessential travel”? There’s the rub, how do you define “nonessential travel”?

As for illegal aliens,

At the direction of the Centers for Disease Control and Prevention, the Department of Homeland Security will suspend entry of all migrants "seeking to enter the US without proper travel documentation" -- for both the northern and southern border, Wolf said Friday. Migrants who are apprehended at the border will either be quickly removed or repatriated to their origin country, Wolf added.

Shouldn’t that always be the case?

The plan was developed in conjunction with the Mexican government.

…Mexican Foreign Secretary Marcelo Ebrard said, "After the meetings we have had, very intense and long last two days and nights, what has been achieved is that the measures for reducing the risk of propagation of the virus will not affect the substantive economy activities of Mexico and the United States and of the border region." Ebrard also maintained that all "essential movements shouldn't be affected."

Several days later, Mexican President AMLO still didn’t consider the border closed. This is what he said in his morning press conference on March 23:

”…we managed to keep the border with the United States from being closed, for that I thanked President Trump. The fundamental thing is that commerce, the economy, the free flow, the movement of persons who must go the United States or to come to Mexico for reasons of health, education, personal development, family matters, they can do it [cross the border]. Only those visits which are not considered necessary are limited. [LOL, what’s left?] …Imagine the damage of closing the border.

Versión estenográfica de la conferencia de prensa matutina | Lunes 23 de marzo de 2020 (“Stenographic Version of the Morning Press conference, Monday March 23, 2020”), Presidential Website, March 23, 2020

Even with the Coronavirus, AMLO doesn’t want to close the border with the United States.

(As of the night of March 22, Mexico had 316 cases of coronavirus, 64% being male.)

According to the Washington Examiner

Customs and Border Protection officials are defying the Trump administration’s directive to block all nonessential foreign travel into the United States from Mexico, allowing noncitizens claiming to be on shopping trips to continue entering, according to two officials involved in the implementation of the order.  CBP employees in Arizona told the Washington Examiner Saturday they were instructed Friday night at the start of the executive order and again this morning not to turn around noncitizens who said they were coming in to shop, visit family, or for medical appointments. By Saturday morning [March 21], “hundreds” of vehicles that should have been blocked at the port of entry had been allowed through, two officials said. “We're letting them through. And that's pretty much the gist of it,” one official said. “Nobody's enforcing it. It was put up — the president put it out. The chief patrol put it out. And we're just not doing it.”

Claim they're going shopping: Border officials allow hundreds of Mexican vehicles to cross despite Trump ban, by Anna Giaritelli, Washington Examiner, March 21, 2020

At the end of their article there is an update:

UPDATE: Saturday night, after publication of this story, sources used for this article said agents in the areas they were aware of had started turning away Mexicans claiming they wanted to enter to shop or for tourism.

That was Arizona. Meanwhile, farther west, San Diego Union-Tribune came out with an article entitled Coronavirus border travel restrictions start to impact daily life, by Gustavo Solis,  March 21, 2020.

U.S. citizens, legal permanent residents, people with work visas, and those traveling for education or medical reasons are still allowed to travel freely across the border with proper documentation. The travel restrictions created an unusually quiet scene at the border Saturday morning (March 21).The sidewalks, usually bustling with people running errands, were empty, as were the pedestrian lanes into San Diego. U.S. citizens and green-card holders who crossed into San Diego Saturday morning noted that the new travel restrictions had virtually no direct impact on them. “It’s business as usual,” said Neil Adams, a U.S. citizen who was coming back to San Diego after a couple of days of eating fresh lobster and visiting family in Rosarito. But for many others whose lives straddle both sides of the U.S.-Mexico border…the restrictions are already having an impact.

The article included three anecdotes about Mexicans who weren’t allowed in: 1) A Tijuana factory worker who works in a respirator factory, who pays his phone bill on the U.S. side because it’s cheaper, 2) A 63-year old grandmother intending to go to San Diego to care for her grandchildren while their mother works from home but “require so much attention that their mother cannot get any work done.” 3) A Mexican who has a post office box in San Diego.

However, getting into Mexico doesn't seem to be a problem.

The new travel restrictions were not as heavily enforced for people traveling from the U.S. into Mexico at San Ysidro Saturday morning. A San Diego Union-Tribune reporter crossing south walked by Mexican customs officials without showing a passport or being asked any questions about the purpose of the trip.  

A tighter U.S.-Mexican border would be better for both countries, though the Mexican government and many Mexicans don’t see it that way now.