Nogales, Arizona (CNN) When Vice President Mike Pence traveled to this border city last week to meet with Border Patrol agents and Customs and Border Protection officers and speak to press near the border fence west of town, his goal, as he put it in a tweet , was to "deliver a clear message" from President Trump demanding further immigration crackdowns to "keep our country safe."

But Pence did not spend time in the city of Nogales itself. Had he done so, he might have heard a conflicting message from people in the twin cities known as "Ambos Nogales" (or "Both Nogales"): The harshness and unpredictability of Trump's border security policies have made their daily lives more difficult and precarious, not safer.

Nogales, Arizona, population 20,000, and its Mexican sister city of Nogales, Sonora, roughly 10 times larger, have long depended on one another's cross-border business to thrive. Many local extended families straddle both sides of the border. There are three main legal crossing points: one downtown just for pedestrians; another, also downtown that also allows passenger vehicles; and one at the western edge of town that focuses on commercial vehicle traffic while also allowing those on foot or in private vehicles.

Every day, on average, more than 9,300 people walk across the border -- backpack-toting students on their way to school, workers, shoppers, tourists. Going south, there's no wait; walking into the United States, it's a different story. Nearly 9,900 passenger vehicles and more than 900 commercial trucks cross, too, hauling American produce and products south and Mexican produce and goods north.

At the huge refrigerated produce warehouse of Chamberlain Distributing Inc., a few miles north of the border, co-owner Jaime Chamberlain could barely contain his frustration talking about Trump's policies on Wednesday, as workers driving forklifts loaded boxes of fresh tomatoes, squash, peppers and cucumbers aboard trucks headed for destinations across the United States.

Jaime Chamberlain, co-owner of Chamberlain Distribution Inc., showed boxes of Mexican gray squash on the US side of the border. Unpredictable border policy is making it difficult to plan.

"I need some sort of stability to grow my business," he said. "When the president of the United States says, 'I'm going to close the border; I want to close the border now; now I'm going to give Mexico a year and then maybe I'll close it' -- how do I plan three, four, five years ahead? How do I plan ahead when he's saying at any point in time the ports of entry could be closed?"

As CNN reported last week, on March 21 Trump privately ordered senior administration officials to close down the El Paso, Texas, port of entry the next day, and wanted to follow with other port closures. Officials were ultimately able to talk him out of it.

Publicly, Trump threatened on March 30 to close the border entirely. A few days later, he said he'd give Mexico a year, then consider imposing tariffs or closing the border.

Even short of such wholesale measures, volatile border policy is already affecting staffing at ports. On March 27, the Department of Homeland Security announced that up to 750 CBP officers would be indefinitely reassigned from their duties at ports of entry to help Border Patrol agents handle surging numbers of undocumented migrant families and asylum seekers crossing at or between ports. About 40 of those officers were taken from the Nogales port of entry, Chamberlain said he was told on a CBP conference call.

Chamberlain, who said his company imports more than 150 million pounds of Mexican fruits and vegetables a year, said all this uncertainty led him on Tuesday to cancel a planned $1.6 million investment to expand his business with a grower in Mexico.

"I get it, we have a problem with so many migrants and asylum seekers," he said. "But you cannot fix it by making the ports of entry weaker, and that's what you're doing."

At Nogales' Mariposa Crossing, the one primarily dedicated to commercial vehicle traffic, CBP has in recent years opened the port on Sundays from February or March to May, during the peak months for Mexican fruits and vegetables. But the shift of customs officers from the port of Nogales led CBP last weekend to halt that program for this year, after just two Sundays, said Lance Jungmeyer, president of the Fresh Produce Association of the Americas, a Nogales-based organization that represents produce importers.

"In Arizona, if the port is closed down on Sunday, companies have to think about sending their produce somewhere else," said Jungmeyer. "It's harmful to us."

Jungmeyer noted that shifting customs officers over to help the Border Patrol is drawing on an agency that has already been short-staffed at ports of entry for months. According to the National Treasury Employees Union, which represents customs officers, as of last month CBP had 1,600 officer vacancies and was seeking funding for 1,900 additional hires. In Nogales, the union said, customs officers routinely were being asked in recent months to work back-to-back eight-hour shifts to make up for the shortfall.

Jungmeyer said he worried that reducing the number of customs officers could embolden drug smugglers, who send the vast majority of hard drugs directly through ports of entry rather than between them, as Trump has claimed. On March 22 and 23, days before DHS announced the shift, customs officers at Nogales's Mariposa Crossing seized nearly 187 pounds of cocaine, heroin, methamphetamines and fentanyl, worth an estimated $3.1 million, from three vehicles. A week ago, customs officers at the downtown Nogales crossing seized nearly 93 pounds of meth, cocaine and heroin worth an estimated $724,000 from two vehicles and a woman on foot.

Beyond commercial traffic, the shortage of CBP officers affects other everyday crossers, too.

Down on North Arroyo Boulevard on the Arizona side on Wednesday afternoon, three high school students walking toward the border and back to their homes in Nogales, Sonora, stopped outside a money exchange business to chat with a reporter. Many students on the Mexican side have dual citizenship and cross daily into the United States for school. But these days, unpredictable delays at the border mean making a very early start to avoid arriving late.

"It's worse now," said Laysha, a junior. (CNN is using only first names because the students are minors.) She said the wait times have grown longer but also less predictable in recent weeks. "It can be half an hour, it can be an hour," added Diana, also a junior.

To get to Nogales High School on time, the girls said, they now leave at 5:30 a.m., two hours before classes start, to make sure they can get across the border and catch a bus for the 4-mile trip. "If we're early, we just go to the cafeteria," said Nicole, a sophomore.

Migrants waited to be fed at a soup kitchen operated by the Kino Border Initiative in Nogales, Sonora. The wait to have an asylum bid heard at the border has soared since January.

Then there are the asylum seekers and other migrants trying to seek legal admittance at the port, who face increasingly long wait times to get a hearing. Roughly a mile away, on the Mexican side of the border, Arturo Garcia, his wife Rosario, and their four children walked past a graveyard decked colorfully with flowers and ribbons that afternoon to line up with more than 100 other migrants outside a soup kitchen run by the Kino Border Initiative, a Catholic humanitarian organization. Garcia, who used to harvest avocados, said they fled from the town of Tlacotepec, in the southern Mexican state of Guerrero, because of fighting between rival cartels.

"We came to Nogales because we were told it would be faster to cross here," he said. But the Garcias have been waiting for just over a month, "and we're told it will be another month and a half, maybe more, before it's our turn," he said.

In the Kino's dining area, advocacy director Joanna Foote Williams helped a migrant woman pick out some donated clothes. The typical wait for asylum seekers has increased sharply since December, Williams said, as the list maintained by another aid group of those waiting on the Mexican side to make asylum claims has grown to more than 400 people from 150.

"CBP is only processing about three families a day," Williams said. That number couldn't immediately be verified. As CNN has reported , although CBP had said for months it is turning back asylum seekers because it doesn't have the capacity to handle them, there is some evidence the agency has limited the number of asylum claims even when it has capacity to process more people.

A section of the border fence with razor wire in Nogales, Arizona, looking south into Mexico.

Downtown, pedestrians avoid walking or standing too close to the 20-foot border fence. That's in part because DHS recently had the military drape the fence in concertina razor wire, which has been controversial. In February, Nogales' city council passed a resolution asking the federal government to remove the razor wire, which Mayor Arturo Garino called unnecessary and dangerous.

Border Patrol agents stationed at the fence on Tuesday and Wednesday declined to give their names. One said he had found the razor wire does help with marijuana smugglers who go over the fence.

"It slows them down ... a little," he said. "They don't come over as often."

Several Border Patrol agents said they'd heard about Trump's recent comments in Calexico, California, in which he told Border Patrol agents to ignore court rulings and turn away asylum seekers. Two senior CBP leaders told Congress on Tuesday that if Trump were to issue such an order, the agency would nevertheless follow the law.

In Nogales, one of the few Border Patrol agents who would speak to a reporter agreed.

"I'll just say, we ask them to follow the rules, so we should follow the rules," he said.