Gas prices have been falling in South Dakota and the nation over the past month. According to GasBuddy.com, the average price for a gallon of gas in South Dakota on Monday was $3.48. The national average was $3.50. A month ago South Dakotans were paying an average of $3.57 for a gallon of gas. The national average is at its lowest point since March of this year. Patrick DeHaan, senior petroleum analyst for GasBuddy.com, joined Dakota Midday and discussed the reasons for the mid-summer gas price decline.