Who grows the potatoes.

Fast-food chains don't make french fries. They cook them, package them, and sell them. The actual making of the fry — selecting potato varieties, washing, cutting, blanching, par-frying, flash-freezing, and shipping — happens upstream at a potato processor. Three companies dominate the North American side of that supply chain. Everyone else is a fraction.

If you know a chain's processor, you can predict most of what you need to know about its fries: potato variety, cut geometry, par-fry oil, salt treatment, and the small supplier-level choices that end up on the chain's ingredient list regardless of what the chain itself believes it ordered.

J.R. Simplot.

Simplot is the largest. The company was founded in Boise, Idaho, in 1929 by Jack Simplot, who built a potato empire during the Second World War selling dehydrated potatoes to the US Army. The company's defining pivot came in 1965, when Simplot's Ray Dunlap and a handful of food scientists convinced Ray Kroc to standardize McDonald's fries on a frozen potato produced in Idaho, par-fried, flash-frozen, and shipped. That decision made Simplot McDonald's exclusive fry supplier for decades, and it still accounts for a significant chunk of McDonald's North American fry volume.

Simplot's Portage la Prairie, Manitoba plant — the one that occasionally pops up in search queries without context — is the specific facility that supplies McDonald's Canada. The Canadian recipe is genuinely different from the US recipe: no beef-derived natural flavoring, a sunflower-oil-based flavor retention step instead. The reason the Canadian fry can be meaningfully different is that it's produced at a different Simplot plant with a different production line. The chain doesn't make this decision at the restaurant level; the processor does, under a per-market contract.

Who they feed: McDonald's (primary US and Canadian supplier), plus a long list of grocery store brands, foodservice distributors, and smaller QSRs. Simplot private-labels for retail and sells under its own brand to foodservice.

Signature potato: Russet Burbank. The variety McDonald's standardized on in 1965 — which still dominates the chain's supply chain — was developed in Colorado in 1908 and remains the single most-grown potato variety in North America. Simplot's growers are concentrated in the Pacific Northwest.

McCain Foods.

McCain is the Canadian answer to Simplot — and in many global markets, the dominant player. The company was founded by the McCain brothers in Florenceville, New Brunswick, in 1957. Still privately held, still headquartered in the same small town. McCain operates processing plants across Canada, the US, the UK, continental Europe, Argentina, Australia, and India.

McCain's US business supplies a mix of chains and foodservice distributors. The company's processing geography means it dominates in Canada and ships into northeastern US markets efficiently, with a smaller but real presence in the broader US.

Who they feed: Globally, McCain's customer book includes most major QSRs in some capacity. In the US specifically, McCain supplies a substantial share of Burger King's North American volume, plus several of the smaller chain customers that Simplot doesn't service directly. The exact brand-to-processor mapping is proprietary and changes with contract renewals.

Signature potato: McCain works across multiple varieties by region. Russet Burbank in North America; varieties better suited to European growing conditions in continental Europe. The company's agronomy program is one of the most sophisticated in the industry and underwrites a lot of the chain-level consistency McCain-fed brands achieve.

Lamb Weston.

Lamb Weston is the US-focused specialist. Originally part of ConAgra, Lamb Weston was spun off as a public company in 2016 and has operated independently since. The company is headquartered in Eagle, Idaho — a few miles from Simplot's Boise campus. The two companies compete directly for grower contracts across the Snake River Plain, and the rivalry is friendly but constant.

Lamb Weston's business is primarily foodservice and QSR, with a smaller presence in retail. The company's product catalog is deeper than Simplot's or McCain's — waffle fries, crinkle cuts, battered fries, premium "steakhouse-style" cuts, sweet potato fries. If a chain's fry is unusual (hand-cut-look crinkle, lattice, ridge, spiral), there's a decent chance Lamb Weston is the processor.

Who they feed: Wendy's, Taco Bell, Chick-fil-A (confirmed waffle-fry supplier), and a long list of other QSRs. The Chick-fil-A relationship is particularly tight — Lamb Weston developed the waffle cut geometry for Chick-fil-A originally, and the chain's waffle fry has stayed proprietary to that supply arrangement.

Signature potato: Russet Burbank for standard fries; selected waxy varieties for premium cuts. Lamb Weston's growers are concentrated in Idaho, Washington, and Oregon, with newer processing capacity in the Columbia Basin.

Everyone else.

Cavendish Farms. Owned by the Irving family's conglomerate in New Brunswick. A smaller potato processor than McCain but still substantial regionally, especially in Atlantic Canada and the US Northeast. Supplies some Burger King and smaller chain volume.

In-store processors. Five Guys, In-N-Out, Hopdoddy, Dick's Drive-In, Elevation Burger — the chains that hand-cut potatoes in-store every day — largely sidestep the processor layer entirely. They buy whole potatoes direct from grower cooperatives (Idaho Russets for Five Guys, Kennebec growers in the Central Valley and Pacific Northwest for In-N-Out) and do their own cutting, washing, and par-frying. This is a dramatically more expensive supply model and partly explains why these chains are concentrated in the premium end of the price spectrum.

Mission BBQ, P. Terry's, Dicks, Hopdoddy. Several of the Cold Eight work with local or regional whole-potato suppliers rather than the big three processors. This is a core piece of why their fries taste distinctive — different potato variety, different par-fry process, often different oil, all set by the chain rather than inherited from the processor.

Why the processor often matters more than the chain.

When a chain reformulates its fry, the question "who sets the recipe?" is less obvious than it looks. For a chain whose processor is Simplot, Lamb Weston, or McCain, the processor has strong opinions about what will work at scale. Reformulations happen through conversation between the chain's R&D team and the processor's agronomy and food-science teams. A chain can override its processor's recommendation, but doing so means custom production runs and real cost increases.

This is one reason the industry moves in waves. When McDonald's switched to vegetable oil in 1990, Simplot's par-fry process had to be re-engineered. That re-engineering produced the natural-beef-flavor workaround, which then became available for other Simplot customers who wanted to retain the "beef-fried" taste note without actually cooking in tallow. The invention moved outward from the processor into the broader industry.

Watch for processor-driven movements in 2026-2028. The current seed-oil-vs-tallow conversation is partly a chain-level marketing play (Steak 'n Shake, upcoming announcements) and partly a processor-level supply chain question. Simplot can reconfigure a plant to supply tallow-par-fried product; whether the economics work is a different question. The next wave of tallow-returning chains, if it comes, will likely be announced at the chain level but engineered at the processor level.

Which is to say: the fry on your tray is as much a decision made in Boise, Florenceville, and Eagle, Idaho as it is one made at your chain's corporate headquarters. Often more so.