Gas prices have surged in the U.S., increasing by almost a dollar per gallon on average in the last month, due to the conflict in Ukraine.

But prices can also vary widely by state, depending on government policies, taxes and proximity to oil refineries. The average cost of regular, unleaded gas in the U.S. is $4.33 per gallon, but in nine states, it costs more than $4.50 per gallon, according to gas prices provided by the American Automobile Association.

Here's a look at how much a gallon of gas costs in each state as of Monday, using data from AAA.

The most expensive state to buy gas is California, where a gallon costs an average of $5.74. That's almost $2 more expensive than what you'd pay in Kansas, the cheapest state to buy gas.

Here are the most expensive states to buy gas:

And these are the states where gas costs the least:

The average driver covers 39 miles per day and their vehicle averages 24.2 miles per gallon of gas, according to government data. That works out to $9.26 in gas per day in California and $6.15 in Kansas — a difference of roughly $100 per month.

In 2021, when gas prices averaged $2.86 per gallon nationwide, the average driver was paying only $4.61 per day. That represents an increase to monthly gas budgets by about $80 to $125 in the last year alone. 

However, these prices don't necessarily reflect actual gas usage, as drivers vary in how many miles they clock per day. For example, drivers in Wyoming have relatively cheap gas but they drive 24,069 miles per year on average — nearly twice that of California, according to Federal Highway Administration data.

When will gas prices go down?

Prices for gasoline — which is derived from crude oil — were already elevated this year due to a lack of oil supply, but the latest surge reflects sanctions or bans on Russian oil exports by Western countries over Russia's invasion of Ukraine.

On March 8, President Joe Biden announced a ban on Russian oil imports, and has encouraged U.S. oil companies to step up production, but it's unclear how much time it will take for U.S. oil output to rise.

Based on that news, the Energy Information Administration now projects a crude oil benchmark price of $105 per barrel this year, a $22 difference compared to its February forecast. The last time oil was $100 per barrel was 2015.

Since gas is derived from oil, expect prices at the pump to stay elevated near or above $4 for the rest of the year.

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