WASHINGTON - A poll released on Tuesday showed that 18.2 percent of US residents have experienced times when they could not afford the food in the past 12 months.

In the worst case, one in four residents living in the US state of Mississippi reported there was at least one time in the past 12 months when they did not have enough money to buy the food they or their families needed, according to the Gallup poll.

Residents in the states of Alabama and Delaware are also among the most likely to struggle to afford food, while those in the states of North Dakota, South Dakota and Vermont are among the least likely to have this problem, the poll found.

In 15 US states, at least one in five residents said they had struggled to afford the food they needed at least once during the past 12 months. Residents living in the states of US Southeast and Southwest are the most likely to struggle to afford food, while those living in the Mountain Plains and Midwest regions are the least likely to experience food hardship, showed the poll.

The drought of 2012, the worst since the 1950s, has affected nearly 80 percent of US agricultural land and threatens to drive up the cost of food in the months ahead, as drought-related crop damage is expected to result in a shortage of food supply and rising prices, the Gallup predicted.

The US Department of Agriculture has predicted that the prices of beef, pork, poultry and dairy products could rise within two months, but the full effects of the increase in corn prices for packaged and processed foods will likely take 10 to 12 months to appear on supermarket shelves.

The poll results are based on surveys conducted from January through June 2012 with 177,662 US adults.