Americans will spend billions on Halloween candy and costumes this year, but it will be less than the 2012 level as worries about the economy put a lid on consumption.

According to a National Retail Federation survey, Americans will spend an average of $75.03 on candy, costumes, decorations and parties in 2013, down about 6 percent from $79.82 last year.

Halloween is the fourth most-popular spending holiday in the United States and this year retailers should expect about $1 billion less in spending than 2012. 

Though Halloween participation hit a record low of 58.7 percent of consumers polled in 2007, this year only 65.8 percent will take part in the holiday, down from 71.5 percent last year. 

"Despite the anticipation of the popular fall event, one-fourth of U.S consumers say the state of the economy will impact their Halloween spending plans," the NRF said. The group's survey was based on a poll of 5,290 consumers during the week of Sept. 3.

Nearly one-third of people said they would be buying less candy this year, though $2.8 billion dollars will still be spent on candy and 72 percent of Americans plan on giving it out.

The most-popular candy so far this year is Reese's, with total sales of nearly $510 million, according to market-research firm Information Resources Inc.

The chocolate-peanut butter candy is owned by Hershey Co. (NYSE:HSY), which accounts for nearly 49 percent of consumer spending, surpassing M&M's, which is owned by Mars Inc., as America's favorite for 2013.

Snickers, another Mars brand, had the most-positive mentions on social media last year, according to Mashable. M&Ms received the most-overall mentions and were the most-popular candies on Pinterest.

The online aggregator will be popular this year as well. According to the NRF survey, nearly 1 in 10 people will use the site for costume ideas -- up from 7.1 percent last year.

This should be helpful for the 18.1 percent of people who plan on making a costume instead of buying -- one in a slight increase from 2012.

Costume choices will be conservative in 2013, according to the survey. The top choices for adults were witches and batman characters, though vampires and pirates also scored high.

Nearly 8 percent of people said they will dress up their pets, which translates to $330 million in additional spending. Top choices for dogs include pumpkin and hot dog costumes.