Definition: In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.
Input: The total length of the continental border is 1,954 miles (3,145 km). From the Gulf of Mexico, it follows the course of the Rio Grande (Rio Bravo del Norte) to the border crossing at Ciudad Juarez, Chihuahua, and El Paso, Texas. Westward from El Paso -- Juarez, it crosses vast tracts of the Chihuahuan and Sonoran deserts to the Colorado River Delta and San Diego -- Tijuana, before reaching the Pacific Ocean.
Output:
where is the border between mexico and us