This statistic shows why McDonald's is the most popular fast food restaurant in the United States by a long shot

McDonald's is an huge force in the fast-food industry - and it's just getting more powerful.

Last quarter, 32% of all quick-service restaurant visits were to McDonald's locations, according to xAd's report on foot traffic trends, which used the location-based marketing firm's geo-boundary technology to gauge the foot traffic of 12 of the biggest quick-service restaurants. For comparison, the chain with the next largest slice of the foot traffic pie was Starbucks, coming in at 11%.

That's right - three times as many people visited McDonald's in the first quarter of 2016 as any other quick service chain, according to the study.

But it might just boil down to sheer number of locations.

"A lot of it comes down to the sheer number of business locations," Sarah Ohle, xAd's senior director of global research, told Business Insider of the chain, which has 14,000-plus locations in the US. "McDonald's does have the biggest chunk of revenue, because they're such a fast-food behemoth."

However, Ohle acknowledged that the fast-food giant's foot traffic also reflected the chain's recent comeback.

McDonald's same-store sales in the US increased 5.4% last quarter, thanks to the ongoing popularity of all-day breakfast, which launched in October, and momentum from the McPick 2 promotions.

Also important is customer's loyalty to McDonald's. While the fast-food giant is often criticized, customers that eat at McDonald's are the least likely to visit any other quick-service brands.

For example, while 37% of KFC's customers visited McDonald's last quarter, just 5% of McDonald's customers ate at KFC.

"If [you] don't go to fast-food chains as much, and you're on a road trip or have a late night craving, the first brand that's going to pop into your mind is the one you're most familiar with and most loyal to," says Ohle. "McDonald's has had such a strong brand presence for such a long time, and now with the all-day breakfast push, they've had a kind of resurgence."

McDonald's sheer size means that when it grows sales, even by just a few percentage points, other chains suffer. Understanding customers' loyalty to the brand, as well as just what an enormous portion of fast-food customers are eating at McDonald's, is key to understanding the restaurant industry - and McDonald's success.