CHARLOTTE -- North Carolina's tax-free weekend is underway and shoppers are hitting the stores, hoping to save money on back-to-school essentials. Sales tax holidays like this one are designed to spur economic growth.

Americans are expected to spend more than $30 billion on back to school needs this year, according to numbers from the National Retail Federation. The latest measure of consumer confidence out this week showed an unexpected jump in shopper sentiment from where it was in June. That could be a sign that people are more likely to spend money during the next six months.

Some shoppers say they're more likely to spend now than they were a year ago.

"A year or two ago I would have, even if it was tax free, been like yeah I can't do clothes right now, need to wait until it's a little more pressing," said shopper Jessica Zingher. "But I feel a little more comfortable now being like I can splurge a little."

Consumer spending accounts for about 70 percent of our nation's economic activity so any change in shoppers' willingness to spend could have a significant impact on Wall Street and Main Street.

The National Retail Federation says shoppers it surveyed plan to spend about $85 more on back to school items this year than they did last year.