"The U.S. State Department issued a record 7,300,667 passports in fiscal year 2003, which ended Sept. 30, including first-time passports and renewals. The record followed two years of declining passport numbers, according to the departments Bureau of Consular Affairs. The previous record of 7,292,182 was set in 2000. The increase brings the total number of valid passports to an estimated 59 million or about 21 percent of Americans, the highest percentage ever. Surges in passport applications usually indicate increased overseas travel by Americans, especially to Europe, as they did in the years 1993 through 2000. While this was not the case in 2003overseas travel has declined because of the Iraq war, the SARS outbreak in Asia and concerns over the economythe passport figures may be a strong positive indicator for 2004."
http://www.travelagentcentral.com/travelagentcentral/article/articleDetail.jsp?id=75568
Most recent data indicates 21%. That is still pretty low for a developed country.
I agree with the need to tighten border controls. However, there will be an economic cost to the tourism industry.