Tom Winter started his hamburger food truck in Missoula, Mont., almost two years ago, focused on selling locally produced food to local people at a price they could afford.

As the business — Gary’s Local Burgers — expanded to three locations, Mr. Winter kept the price of his burgers steady, at $6, a number he posted on huge signs.

But last month he printed new signs with a new figure: $6.95.

Ground beef was at its highest average price on record in May at $5.98 a pound, according to the Bureau of Labor Statistics. That cost was 16.2 percent higher than 12 months earlier. Other cuts of beef, including sirloin steaks and chuck roast, also reached record highs in the first half of 2025.

Even though he’s buying beef and selling hamburgers locally, Mr. Winter could not escape a market that has become more expensive to operate in. Prices are up because the number of cattle available for beef is at its lowest level since the 1950s.

The number of beef cattle in the United States is down to 27.9 million, a 13 percent decline since 2019, and the overall cattle inventory is the lowest it has been since 1952, according to the Agriculture Department. Consumer demand has remained steady in recent years.

“I pledged personally that we would keep them at $6, and I was forced to go back on my pledge and increase it by 95 cents,” Mr. Winter said of his burgers, adding, “We just did not understand that prices would do this.”