Updated

More Americans are crossing the Mexican border, but it's not as tourists — it's to take advantage of that county's lower gasoline prices.

In Southern California, where gas prices in San Diego County are approaching $5 a gallon, residents are heading to Tijuana, where gas is six pesos per liter, or $2.50 a gallon, The Wall Street Journal reported.

"It's a daily thing for some: run across the border and fill up," James Blue, who owns an auto shop in downtown San Diego, told the newspaper.

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Some even are going as far as installing extra-large fuel tanks in pickups and other work vehicles, allowing them to bring back enough fuel to sell to neighbors and co-workers, the newspaper reported.

Gustavo Robinson, a plumber who works for a public school district in California, got a 75-gallon tank installed in his vehicle in addition to his original 28-gallon tank. He estimates that using the two tanks to fill up in Mexico will save him at least $200.

The Mexican government is heavily subsidizing the gas prices there so the country's poor can afford to fill up. As a result, some stations are refusing to serve Americans.

Click here to read more on this story from The Wall Street Journal.