Fireworks?

But I just googled and found this
"According to US Census data, July is the most popular month to have a baby"
http://www.sctimes.com/apps/pbcs.dll/article?AID=/20060726/ENT/107270001and also this
"July is the most popular month for U.S. domestic travel with 130.4 million person trips, followed by August (122.8 million), June (109.6 million) and May (107.9 million).
Source: Travel Industry Association of America’s Domestic Travel Market Report, 2005 Edition"
http://sdvisit.com/tools/research/national.aspBut neither are 'official' sites so i guess you can take it with a grain of salt - but perhaps you could look at thier sources to get some official word.
Hope that helps