In an effort to improve its border security measures, the Border Patrol in Arizona is seeking to build permanent checkpoints in Ajo, Tubac and Huachuca City. Replacing the three temporary checkpoints with permanent ones would have a price tag ranging from $40 million to $50 million. The Tucson sector while only accounting for about 13% of the U.S.-Mexico mile frontier is the busiest of all the border patrol sectors and accounts for around 37% of the illegal immigrants detained. In addition, the Tucson sector accounts for nearly 50% of the marijuana confiscated at the border. Currently there are only temporary checkpoints which many Border Patrol officers claim to be less effective because they lack certain resources. The current strategy in Arizona like in other border states includes setting up barriers like fences, cameras, sensors, checkpoints and patrols. Permanent checkpoints have such capabilities as x-ray truck scanners and data links that allow names to be checked against criminal databases. The desert terrain in Arizona slows down immigrants and the dust generated from vehicles they travel in often gives away their location. However, the Tucson sector still attracts many immigrants trying to get to the United States since the lack of permanent checkpoints results in one less challenge they have to face. As of 9/11, the Border Patrol has built only one permanent checkpoint near Laredo (Texas), but the number of detainees compared to other checkpoints has not changed significantly. For now, a combination of temporary, permanent and internal checkpoints will continue.