It's spring. The flowers are out at Independence Hall and so are the tourists. If it seems like there are more of them, well, Philadelphia may be on track to have another record number of visitors.

Last year, 38.8 million people came to Philadelphia from around the country. About 80 percent of those visitors traveled from states along the East Coast.

And they're sticking around longer than in the days when the average visit was just a couple of hours, according to Meryl Levitz, CEO of the Greater Philadelphia Tourism Marketing Corporation.

Before the late '90s, it was "sort of a drive by," she said. "The Liberty Bell and, oh, let's get a cheesesteak and that sort of thing on the way to or from D.C."

Now, the average extends over two and a half nights.

There's clearly no check in at the border, so if you're wondering where those numbers come from, it's a combination of survey data and industry data including hotel occupancy. Levitz's organization compiles the numbers and releases them all in its annual report.

The reports also indicates that investments in the Benjamin Franklin Parkway museum district have paid off. Visits were up 18 percent last year -- not counting attendance at the new Barnes Foundation museum that opened up last summer.