Pope Francis is scheduled to arrive Wednesday morning in Ciudad Juarez, just across the U.S.-Mexico border from El Paso.
He will hold a Mass at 4 p.m. with about 450,000 people from both sides of the border expected to take part in the celebration.
The visit will be the closest a pope has been to Texas since a San Antonio visit in 1987.
Security will be the top priority Wednesday as the Catholic faithful flock to the historic event.
Anyone crossing the border can expect delays and increased security checks at ports of entry.
U.S. Customs and Border Protection officials said the bridges will remain open 24/7 during the pope's visit.
Officials expect a lot of people visiting Mexico will be bringing back items blessed by the pope, some of which are not allowed in the U.S.
Some of the items not allowed include soil and plants. Visit the CBP website for a full list.