U.S. gas prices jumped to an average of $4 a gallon again Monday as the U.S. and Iran launched more attacks. According to motor club federation AAA, the national average for a gallon of regular gasoline is now back to $4. The average price a year ago was $3.14 a gallon. The price is a national average, meaning drivers in some states have been paying well over $4 a gallon for a while now, while others pay less. Prices vary between states due to factors ranging from nearby supply to differing tax rates. People around the world are also dealing...