Higher gas prices have been an unfortunate trending topic for much of 2026. Many states in America are seeing higher gas prices and diesel prices at the pump, leading consumers to spend millions more this year than they would have last year.

Here's a look at the states that are seeing the biggest increases and which states have the highest and lowest costs.

Biggest Increases

Gas analyst Patrick De Haan (@gasbuddyguy) shared on social media that the price of regular gas and diesel continued to rise over the past weekend.

De Haan shared that as of Sept. 21, the average price for regular gas was $4.44 per gallon nationwide. This is an increase of 18.5 cents from the prior week and an increase of $1.28 from the prior year.

For diesel, the average price nationwide is $6.49 per gallon, up 30.7 cents per gallon from last week and up $2.83 per gallon from the same time last year.

Prices rose in nearly every state, with the Great Lakes region hit particularly hard, with costs rising over the weekend due to refinery issues.

Here are the five states with the largest increases in regular gasoline for the past week, with the increase from the prior week:

1. Michigan: +61.2 cents per gallon
2. Indiana: +43.7 cents
3. Illinois: +42.5 cents
4. Ohio: +35.1 cents
5. Wisconsin: +33.7 cents

Here are the five states with the largest increases in diesel fuel for the past week, with the increase from the prior week.

1. Michigan: +66.2 cents per gallon
2. Indiana: +65.2 cents
3. Ohio: +57.8 cents
4. Illinois: +51.5 cents
5. Kentucky: +50.1 cents

The states of Michigan, Indiana, Illinois and Ohio appeared on both lists with the largest price per gallon increases.

Cheapest and Most Expensive States

While nearly every state saw a rise in the average price of gasoline and diesel fuel last week, some states remain significantly lower and higher than other states and the national average. Here's a look at the cheapest and most expensive states to fill up in, with prices as of Sept. 21.

Cheapest Regular Gas

1. Texas: $3.94 per gallon
2. Mississippi: $3.95
3. Louisiana: $3.98

Most Expensive Regular Gas

1. California: $6.14 per gallon
2. Washington: $5.51
3. Hawaii: $5.47

Cheapest Diesel Fuel

1. Texas: $5.96 per gallon
2. Louisiana: $6.01
3. Oklahoma: $6.02

Most Expensive Diesel Fuel

1. California: $8.38 per gallon
2. Washington: $7.37
3. Hawaii: $6.95

The data shows that states in the South near many refineries have lower prices, while states out West that are farthest away from the refineries have the highest prices.