A century ago, people had never even heard of credit cards, yet today, we count on them to pay for everything from movie tickets to doctor’s appointments. That’s why it can come as a surprise when we pull out our favorite credit card, only to learn the business does not accept it. 

If your preferred payment method is with an American Express card, it pays to know where it can — and can’t — be used. 

Where American Express may not be accepted

American Express clearly states that its cards are accepted by 99% of U.S. merchants that accept credit cards. It’s primarily when shopping in smaller retail stores, farmers’ markets, some restaurants, and one giant U.S. retailer that American Express is not welcome. Here are five places you may want to have a Mastercard, Visa, or other payment method available, just in case: 

1. Mom-and-pop shops: Say you’re traveling and come across a quaint mom-and-pop shop. Before shopping, you may want to ask which cards it accepts. 
2. Independent restaurants: Small restaurants sometimes operate on a shoestring budget, making it more challenging to pay Amex’s fees. 
3. Small retailers: We’re not saying no small retailers accept American Express, but that a small business is less likely to accept it than a larger, more established establishment. 
4. Foreign businesses: According to Experian, you may have better luck paying with American Express if you’re traveling in a large city in Australia, Canada, India, Mexico, Singapore, or the United Kingdom. On the other hand, you won’t find a business that accepts American Express anywhere in Cuba, Sudan, Russia, or Belarus. 
5. Costco: At one time, Costco was partnered with American Express but not the other three major credit card networks. At the time, shoppers complained about being unable to use their Visa or Mastercard credit cards. In 2016, Costco broke up with American Express and partnered with Visa. Today, it’s the only credit card the warehouse giant accepts at checkout.

Note: There are ways around the Visa-only rule at Costco. For example:

• Apple Pay, Google Pay, or Samsung Pay may be used at checkout, no matter what funding source the mobile payment is linked to.
• Visa and MasterCard FSA and HSA cards are accepted at pharmacies and in the optical and hearing aid departments.
• Apple Pay is an acceptable source of payment at U.S. Costco gas stations.
• Visa, MasterCard, and Apple Pay are all accepted when making a purchase through Costco.com.

Why would a retailer not accept American Express? 

Each time a retailer accepts payment via credit card, it must pay merchant fees. And here’s where things get tricky: The amount it pays depends on the card. 

Although American Express offers OptBlue to help small businesses qualify for lower fees, the fees still tend to be higher than those of competitors. Here’s a sample of what we mean:

• MasterCard Starting interchange fees of 0% + $0.10
• Visa Starting interchange fees of 1.15% + $0.10
• Discover Starting interchange fees of 1.56% + $0.10
• American Express Starting interchange fees of 1.60% + $0.10

The interchange fee is only one of the fees merchants face each time they accept a credit card. They’re also responsible for paying a discount rate and an assessment fee. A voice authorization fee is also tacked on when a merchant must call a payment processor to accept card payments. 

While the interchange fee is the merchant’s largest expense when it accepts a card as payment, smaller fees also add up. Considering all the other costs a business faces, the amount it must pay to accept specific credit cards is a legitimate concern. 

Whether you’re attached to your American Express card due to its perks or you’re serious about building up Amex rewards, there’s an easy way to find out where you can use your card. This American Express map allows you to search by business name or to type in the area you plan to shop. Once you’ve typed in the business name or location, a list of businesses appears, assuring you that your card is welcome there. 

A credit card accepted by 99% of U.S. businesses that accept cards provides pretty great coverage. However, there’s no harm in knowing where it can be used before leaving home.