The higher gas prices go, the more the math on a Costco membership starts to make sense

Drivers fill their tanks at a Costco gas station in California as fuel prices rise amid the war with Iran.

Frederic J. BROWN / AFP via Getty Images

• Average US gas prices topped $3.60 this week after Trump's war with Iran disrupted oil supplies.
• Costco, meanwhile, sells gas about $0.20 per gallon less than nearby stations.
• The wholesale club's price advantage can be bigger in areas with relatively high gas prices.

President Donald Trump's war with Iran is disrupting...