NEW YORK — Who knew the calendar could cause so much vacation heartburn?

For the first time in five years Independence Day falls on a Wednesday, leaving travelers unsure when to celebrate and worrying those who make a living off tourists.

“The midweek holiday seems to have travelers confused,” said Anthony Del Gaudio, vice president of hotel sales for Loews Hotels, which isn’t seeing the normal July Fourth spike in bookings.

Those who sell vacations say this year’s calendar gives Americans more options: Tack on Saturday through Tuesday or Thursday through Sunday to the holiday, or just take the entire week off.

But consumers’ confidence has been waning. Now, some aren’t happy about having to burn an extra vacation day or two to get that long weekend. From 2008 through 2011, the work holiday fell on either Friday or Monday, so employees and their families got an automatic three-day weekend, similar to Memorial Day and Labor Day.

AAA, one of the nation’s largest travel agencies, projects 42.3 million Americans will journey 50 miles or more from home between July 3 and July 8. That’s roughly the same amount that traveled in 2007, the last time July Fourth fell on a Wednesday. Last year, when the holiday fell on a Monday, 40.3 million people traveled. But before you think it’s a big increase, note that AAA’s economists changed how they estimated the number of travelers: They used a six-day period this year compared to five last year.

“In general, we think that travel from last year is pretty flat,” said Shane Norton, a director at IHS Global Insight, which provides economic forecasting and research for AAA.