NEW YORK (AP) — Stores are welcoming a second wave of shoppers in what has become a two-day kickoff to the holiday shopping season.

The big question: How much Thanksgiving shopping will hurt Black Friday, which is relinquishing its status as the start of the holiday shopping season?

Last year, sales on Black Friday slumped 13.2 percent to $9.74 billion, according to ShopperTrak, which tracks data at more than 70,000 stores globally. Bill Martin, co-founder of ShopperTrak, says how stores will fare Friday is uncertain.

With stores pushing more deals earlier in the month, the holiday weekend has become less important. But the period still sets the tone for the shopping season, whose sales are expected to rise 4.1 percent to $611.9 billion. That would be the biggest increase since 2011.