Business is booming at the world's largest wholesale market in Yiwu, China, where retailers are looking for inexpensive items to fill their shelves.

The city's international trade center is an extensive network of 70,000 stalls spread over 12 floors.

But it's not just traders who are watching closely; political observers are also keeping their eyes on it a phenomenon they call the “Yiwu Index.”

The theory posits that the better a US political candidate's replicas sell in Yiwu, the better his chances are in the upcoming election.

In particular, the “Yiwu Index” was a better predictor of Donald Trump's victory in 2016 than pollsters who were convinced throughout the election campaign that Hillary Clinton would be the winner.

With the 2024 election just days away, Beijing is likely to use this theory in monitoring the race.

Yiwu, China, is home to one of the largest wholesale markets in the world. Pictured: A Chinese employee sews a Trump 2020 Keep America Great flag

Merchandising has long been an important part of political campaigns. While candidates often donate their official gear, stores overseas have released replicas of candidates' swag, capitalizing on the increasing polarization of U.S. politics.

Yiwu, in eastern China, is known for providing early insights into the types of goods it sells in the run-up to a presidential election.

But in the market, it doesn't boil down to a science – and there are flaws in using the index to try to predict the outcome.

First, the marketplace rarely sells directly to consumers and relies primarily on wholesalers.

Most often, during this buying phase, retailers may order certain goods in bulk in anticipation of a surge in demand – whether or not it materializes.

Trump supporters are also much more likely to display, wear and purchase items that show their political loyalty than those who support Vice President Kamala Harris — or any other politician.

In 2020, While Chinese-made Trump items outsold those bearing Joe Biden's name, the latter still claimed victory.

Trump's signature red “Make America Great Again” hats are a Yiwu bestseller and a totem of the former president's supporters

The so-called Yiwu Index predicts the winner of the US elections based on the sales figures of the opposing candidates

Harris-Walz's camouflage hats also caused quite a stir in Yiwu, as the first edition sold out in just 30 minutes

Recently, demand in the Yiwu market for camouflaged Harris Roll campaign hats has skyrocketed, which is a good sign for the Democrats.

According to The Telegraph, the entire first print run disappeared within 30 minutes of going on sale.

However, Zoe Liu Zongyuan of the US-based think tank Council on Foreign Relations told the outlet that the index may not be accurate.

“Imagine a scenario where you have a Trump neighbor versus a Democrat neighbor. Trump voters are more likely to show off their MAGA stuff,” she said.

“Democrats, people who vote independently, or undecideds are less likely to spend money to buy these things.” So I would say that the Yiwu index may no longer be an accurate indicator because voter behavior and the way how they show their enthusiasm has changed.

The Yiwu theory suggests that Trump's higher sales compared to his competitors could be an indicator of how likely voters are to go to the polls.

“When everyone said Democrats, Hilary Clinton, would win (in 2016), the index suggested otherwise,” Zongyuan said.

“It's not the Chinese who are buying this stuff, it's the Americans, the delegations, the rallies, these people who are buying it.” Could this be an indicator of how passionate people or voters are? This way you can understand it better.'