Large parts of the United States are still in the grip of one of the worst droughts in living memory.

It's caused havoc among the farmers and ranchers of the Great Plains, but it's causing all manner of legal difficulty too. In the arid south-west of the country, where water has often been the source of conflict, shortages are pitting state against state.

Texas and New Mexico are locked in a dispute that could end up being decided by the US Supreme Court. It's a complex case, but essentially revolves around one key question: is New Mexico living up to its obligations, under a 1938 compact, to deliver enough water from the Rio Grande River to its southern neighbour Texas?

The BBC's Paul Adams, has been on a journey along the Rio Grande, from one end of New Mexico to the other, to find out more.

Produced by: Robert Brown and David Eckenrode

Edited by: William McKenna and David Botti