After this weekend, U.S. citizens won’t be able to return easily to the United States with just a picture ID and a birth certificate. The Western Hemisphere Travel Initiative (WHTI) goes into effect June 1 and every U.S. citizen will need a passport or one of five other documents to cross the border.

A U.S. Customs and Border Protection employee checks a vehicle at the Dennis DeConcini Port of Entry in Nogales. Beginning June 1, U.S. travelers crossing into the U.S. will need authorized documents.

It’s an inconvenience and expense for millions of U.S. citizens who must shell out $100 for an adult passport and wait weeks to receive the document. But the present system is a daily challenge for U.S. Customs and Border Protection, said Thomas Winkowski, assistant commissioner for the CBP Office of Field Operations.

“Our employees are dealing with 8,000 different documents (at border crossings),” said “WHTI boils it down to six documents.”

Winkowski spoke with reporters May 28 at the Dennis DeConcini Port of Entry in Nogales. He’s on a swing through the border areas “to talk about why we’re doing this and why it makes sense,” he said.

CBP must maintain “that delicate balance of facilitating legitimate trade and travel while preventing dangerous things and people from coming into the country,” Winkowski said. “We believe WHTI is an initiative that allows us to strike that balance.”

WHTI changed a longtime policy that U.S. citizens did not have to present documents to re-enter the country at a land crossing (from Canada or Mexico), said Bonnie Arellano, chief public affairs officer with Tucson Field Operations, in an interview.

The 9/11 Commission recommended the passport requirement in its 2004 report “to tighten up the border,” Arellano said.

The six documents CBP will accept are the U.S. passport, passport card, an enhanced driver’s license (that only Washington and New York states currently issue) or one of the “trusted traveler” cards -�“ SENTRI, NEXUS or FAST, Winkowski said.

There is an exception for younger travelers.

“U.S. and Canadian citizens who are 15 years old or younger will still be allowed to travel with just a copy of their birth certificate, as will teens between the age of 16 and 18 if they are part of an adult-supervised school, religious, cultural or athletic group,” states CBP on its Web site.

After June 1, citizens without a passport will be routed to a secondary inspection area, where they will have to wait while customs employees verify their U.S. citizenship, Arellano said.

“A U.S. citizen must be admitted,” Winkowski said. “We recognize that not everyone is going to have a WHTI-compliant document.”

In wintertime, Arizona gets many out-of-state visitors who may not have heard about the passport requirement, Winkowski said. But he estimated that 80 percent of travelers returning to the U.S. will have the right documents on June 1.

“I expect a smooth transition,” Winkowski said. Thirty-nine ports of entry use specialized equipment to rapidly check vehicles and travelers, he said. CBP staff is well trained and computer technicians will be on call.

The federal government spent $16.2 million on its outreach campaign to alert travelers to the new requirement, Winkowski said. As a result, a record 91 million U.S. citizens now have passports and 1.2 million obtained passport cards, good for crossing by land or sea. Air travelers need to carry the passport book.

For more information, visit www.getyouhome.gov.