If President Trump goes through with his threat to close the border with Mexico, Arizona would feel the effects almost immediately.

As a border state, Arizona has a closer tie with Mexico than many other states do —and in terms of the economy, trade, and tourism, it would feel the impact more than many other states.

Many policy details aren't yet known and thus are difficult to predict. But here are some of the possible ripple effects of closing the border.

How large is Arizona's economic connection with Mexico?

It's big.

Mexico is Arizona's largest trading partner. The state sends 30 percent of all its exports to one country: Mexico. That amounts to $682 million in exports over a recent three-month period, according to research by the Eller College of Management at the University of Arizona.

Mexico exports more to the U.S. border states than it does to the rest of the world combined, excluding the United States, according to a report by the Wilson Center, a think tank on global issues.

The Nogales-Mariposa port of entry brings in an enormous amount of winter fruit and vegetables to the United States.

Arizona faced the potential loss of $5 billion in exports and 236,000 jobs if the North American Free Trade Agreement, or NAFTA, unraveled. Those studies, by BMO Capital Markets and the U.S. Chamber of Commerce, also incorporated the value of Arizona's trade ties with Canada, another big trading partner. Negotiators representing the U.S. Mexico and Canada subsequently agreed to replace NAFTA with a new trade agreement, though the new deal hasn't been ratified.

Might consumers feel the pinch from a border shutdown?

Presumably, they would. For example, consider the large amounts of fruits and vegetables that Mexico sends north. If those produce items couldn't get through, supermarket prices would jump as supplies would get scarce.

However, manufactured goods account for a bigger part of the trade picture than produce. Arizona's leading exports to Mexico and other nations include aircraft engines and parts, copper ore, and electrical parts and machinery.

Lance Jungmeyer, president of the Fresh Produce Association of the Americas, said although the winter produce season is winding down, a big harvest of table grapes from Mexico is expected through June.

Would a border shutdown affect retail trade and local tax collections?

Yes. Mexicans regularly cross the border to go shopping, especially in the southern part of Arizona, before returning home.

Border communities such as Nogales, Arizona, depend on sales taxes paid by Mexican shoppers as a key source of revenue. They often are the first to feel the impact of a decline in retail trade, and also feel it more heavily that other areas of the state.

"Retailers in the U.S. border cities know how critical Mexican residents who cross the border and shop for food, clothing, auto parts, and other retail items on the American side are for their business revenues," wrote Vera Pavlakovich-Kochi, an associate professor of geography at the University of Arizona, in a February update.

"City and county governments on the border are also cognizant of the contribution of Mexican shoppers to their sales tax revenues," she added.

How would travel, tourism be affected?

A true shutdown would imply nobody could traverse the border by car, bus, or on foot, heading either north or south. Arizona businesses such as hotels, restaurants and various stores could feel the pinch from a drop-off of foreign tourists. Americans seeking to hit the beach in Rocky Point or other Mexican vacation destinations also might need to adjust their itineraries.

And perhaps more troublesome: How would Americans currently vacationing in Mexico return home, and vice versa?

Holy Week is probably the biggest annual travel holiday for Mexican visitors and shoppers. This year's Holy Week falls April 14-21, so the timing of a border closure — or any change that creates lengthy delays — could have big consequences for businesses all the way north to Tucson, including hotels, shops and restaurants who see a noticeable boon during this period, especially on Easter weekend.

A border shutdown implies land transportation would be impacted, but could it also be extended to airline travel? Even if Trump allowed airline flights to continue, the directive could push up the price of airline tickets, as flying would be the only realistic way to move from one country to the other.

What other fallout might a border shutdown have?

The Mexican peso might drop relative to the dollar, given the much larger importance the U.S. exerts on Mexico's economy rather than the other way around. Ironically, a shift in currency values could worsen America's trade deficit with Mexico by making items made in Mexico cheaper to American buyers — assuming importers could find a way to get them across a closed border.

A border shutdown also could push down U.S. stock prices and otherwise rattle financial markets, which have been skittish when trade disputes percolate to the surface. That could affect 401(k) retirement accounts and other investments held by millions of Americans.

Above all, investors, businesses, and consumers dislike uncertainty. A shutdown might unnerve a lot of people on both sides of the border and prod them to put commercial and personal plans on hold. The business community thought North American trade had been ironed out when negotiations representing the U.S., Mexico and Canada agreed to replace NAFTA with a new trade pact. Now, it could be back on the front burner.

Reach the reporters at russ.wiles@arizonarepublic.com or 602-444-8616, or rafael.carranza@arizonarepublic.com.