While the entire Mexico–United States border has experienced high levels of drug trafficking and other illegal smuggling activities for decades, this activity tends to be concentrated in certain sectors within Texas. Two such sectors are the Rio Grande Valley and West Texas, near the El Paso–Juárez metropolitan area. The high level of legitimate travel and movement of goods and services between border cities in the U.S. and Mexico facilitates the drug business in the area. The majority of the commerce between the United States and Mexico passes through the state of Texas. Due to its multifaceted transportation networks and proximity to major production areas right across the border in Mexico, Texas is a major hub for drug trafficking. According to the National Drug Intelligence Center, drug traffickers commonly use private vehicles and commercial trucks to traffic narcotics throughout the state. The drug organizations usually use the Interstates 10, 20, 25, 30, and 35, as well as U.S. Highways 59, 77, 83, and 281. The Gulf of Mexico also presents a danger to the flow of drugs to Texas; the Port of Houston and the Port of Brownsville enable traffickers to use small vessels and pleasure craft to transport illicit drugs into and from southern Texas.