Swiss watch exports fell 9.4 percent in September from a year earlier, the Federation of the Swiss Watch Industry reported on Friday, the sixth consecutive monthly decline and the longest downturn since 2016, as American tariffs on Swiss goods continued to choke off demand in the industry’s most important market.

Shipments to the United States, which accounted for about 17 percent of the industry’s 26 billion Swiss francs in exports last year, fell 23 percent in September by value. Exports to China fell 11 percent, extending a slump that began in 2024, while Japan and the Gulf states were the only large markets to grow.

“An American customer who used to pay 8,000 dollars for a watch is now being asked for 11,000, and he is finding that he can live without it,” said Jean-Marc Dubois, the federation’s chief economist. “The high end is surviving. The middle is being squeezed from both sides.”

The tariffs, imposed in 2025 after Switzerland and the United States failed to conclude a trade agreement, apply to most Swiss manufactured goods and have been passed on to consumers almost in full, according to the federation. Watches priced between 500 and 3,000 francs at export, the segment that supplies much of the industry’s volume and employment, have been hardest hit, with exports in that range down 31 percent to the American market.

The effects are visible in the Jura valleys. In La Chaux-de-Fonds, a city of 38,000 built on watchmaking, at least five component suppliers have placed workers on reduced hours under Switzerland’s short-time work program, and the cantonal employment office reported 410 applications from the sector in September, three times the figure for the same month last year.

“We make dials for brands you know, and those brands have stopped ordering for the American market,” said Nathalie Vuilleumier, who runs a 45-person dial manufacturer founded by her grandfather. “We have gone to four days a week. If the spring is like this, we will go to three.”

Larger groups have fared better, drawing on deep inventories and shifting stock to Asia and the Middle East, and the very top of the market, watches exported at more than 50,000 francs, actually grew 4 percent. “A client buying a 200,000-franc tourbillon does not notice a tariff,” Mr. Dubois said. “A client buying his first mechanical watch notices everything.”

The Swiss government said this week that negotiations with Washington were continuing. In La Chaux-de-Fonds, few are counting on them. “We have been told a deal is close for a year,” Ms. Vuilleumier said. “We make things that are precise. We would like our politics to be as well.”