The holiday shopping season started as a marathon, not a sprint.

More than a dozen major retailers from Target to Toys R Us opened for 24 hours or more on Thanksgiving Day through Black Friday, the traditional start to the holiday shopping period. As a result, crowds formed early and often throughout the two days.

About 15,000 people were waiting for the flagship Macy’s in New York City’s Herald Square when it opened at 8 p.m. on Thanksgiving. Long checkout lines formed at the Target in Colma, Calif., on Black Friday morning. And at North Point Mall in Alpharetta, Ga., Jessica Astalos, 20, had already been shopping for six hours starting on Thanksgiving night as another wave of shoppers made their way into the mall around 5:30 a.m. on Black Friday.

“I like being around crowds of people all doing the same thing,” said Dalton Mason, 22, of Stockbridge, Ga.

The start of the holiday shopping season has transformed into a two-day event. For nearly a decade, Black Friday had been the official start to the busy buying binge sandwiched between Thanksgiving and Christmas. It was named Black Friday because that was traditionally when retailers turned a profit, or moved out of the red and into the black.

But in the past few years, retailers have pushed opening times into Thanksgiving night. Some like Macy’s opened on Thanksgiving for the first time this year. Others like Gap Inc., which owns Banana Republic, Gap and Old Navy, opened some stores earlier on Thanksgiving than the year before. And many pushed up the discounting that used to be reserved for Black Friday into early November.