Although more than 9 out of 10 illegal immigrants detained at the border are Mexicans, immigrants from other countries are increasingly being detained at the US-Mexico border. 

From the Houston Chronicle:

ore than nine out of 10 illegal immigrants detained at the U.S.-Mexico border are Mexican. But for years, this easternmost sector of the border has had more than its share of what the Border Patrol calls “other than Mexicans” or OTMs. The Rio Grande Valley sector has accounted for as many as half of the border’s OTM apprehensions in recent years while having only one-tenth of the total border apprehensions.

During the first seven months of this fiscal year, this sector has nabbed nearly 11,000 OTMs, accounting for one quarter of its total apprehensions.

Honduras, Guatemala and El Salvador historically are the main sources of immigrants other than Mexico.

After surpassing 2,100 in 2005 and 2006, the number of Chinese immigrants caught along the border fell last year to 837, slightly more than 1 percent of all OTM apprehensions, according to Border Patrol data. In the first eight months of this fiscal year, 512 Chinese were caught.

Border Patrol officials and others familiar with immigrant smuggling say the Rio Grande Valley’s popularity likely stems from being the shortest path into the U.S. from Mexico City and Central America.