Here is an interesting Graphic from Stratfor detailing the major transportation networks that run throughout Mexico.
You will notice that Mexico doesn't have a major river transporting system like the United States. This is unfortunate for Mexico because transporting goods via truck or rail is more expensive than by water. At the most rudimentary all you need to transport goods via water is a raft and if your going upstream a pole or some sort of engine. River's, unlike roads, or rail ways, do not need to be maintained. Moreover, water naturally takes the path of least resistance, which is why you will often find and railways traveling along the path of a river, through harsh terrain.
The lack of a central water way system like the Mississippi river ways makes economic develop more expensive, and therefore, more difficult. These systems are often very difficult to maintain, and during times of extreme economic hardship, are often the first items to fall into disrepair. It's odd that the road that weaves its way through difficult terrain that allows vital goods to travel between two areas will be the first too fall apart. But the distance away from metropolitan centers, and often difficult terrain, creates an undesirable situation around areas where good road ways are needed most.
The US is fortunate that even during a period of times were there are less funds available for road and rail maintenance, that our country benefits from one of the most mild and extensive water transportation networks in the world. The right kind of river serves not only as a economic multiplier, but buffer as well. Rivers are so important that that the ancient Chinese started building what would later be the largest canal system in the world, that now links Beijing to Shanghai. And the early United States spent vasts amounts of money to connect its Superior Lake settlements to the Hudson river.
Nations that do not benefit from an expansive river system will often find their population centers centered around the sea for this very reason. And for some nations that have difficult and a nearly impassible interior, like Brazil it can hamper economic development in some ways. Because Mexico doesn't have a river system, and because their colonial masters never bothered to build an expansive transportation network in the 300 years that Mexico was colonized, its economic development has often grown in fits and start when compared to the more economically stable United States. This is one of the reasons why America is a super power economically and militarily and Mexico has perennially struggled. Mexico isn't doomed for permanent poverty, they are one of the largest exporters of oil to the United States and have one of the largest exlusive economic zones in the world. Because of the lack of a inland waterway system the sea takes on a very important economic significance for the nation. Which is why as Mexico develops that it will focus more on the sea than its interior, which it has historically done. Mexico is currently in the process of modernizing and growing their navy.
This could be the source of future tension with the the largest economic and military super power in the world; especially considering that this focus will be occurring in what America considers her back yard. But that is many decades if not a century in the future. Currently Mexico is in the process of developing without a water way system to aid them, and the pervasive corruption throughout the nation only hinders them further. Though if Mexico had possessed such a system earlier in their development than the course of North American history could have been very different.