Black Friday has always served as the kickoff to the holiday shopping season, but we are seeing a shift in that trend.

Shoppers head into Target just after the doors opened at midnight on Black Friday, Nov. 28, 2014, in South Portland, Maine. (AP Photo/Robert F. Bukaty)

The shopping season continues to start earlier and earlier, and it continues to run later and later. Usually Black Friday is the busiest shopping day of the year.

"That wasn't the case last year. Last year, the Saturday before Christmas was the busiest," said John Holub, president of the NJ Retail Merchant's Association.

Though, analysts expect Black Friday to regain that top spot again this year.

Holub said there are few reasons for the dilution of Black Friday, including retailers rolling out promotions earlier, the rise of online shopping, holiday shoppers procrastinating and Black Friday festivities starting even sooner.

"One of the trends we've see the last few years is retailers opening earlier and that has actually crept Black Friday into Thanksgiving day," Holub said.

The retail industry, he said, is accustomed to ebbs and flows, so the shifting trend has led retailers to adapt.

"I think you are having retailers provide more promotions earlier, more often during the whole holiday season, so there's a lot more opportunity," Holub said. "You can still get really good deals, not just on Black Friday, but on several days throughout the holiday season. It's good for retailers and consumers."

He said he expects the Saturday and Sunday after Christmas this year to be very vibrant shopping days.