http://www.freerepublic.com/focus/f-news/3737324/posts?page=10#10
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The Roosevelt Reservation extends the first 60 feet inside the United States. For the more than 1,200 miles of the Texas border with Mexico however, the border itself is in the middle of the river. 60 feet will often not even reach the bank.
Additionally, we have a binding International treaty with Mexico on managing the waters of the Rio Grande. Any construction that could divert floodwaters must be approved by the International Boundary Commission - and the lower Rio Grande is subject to hurricanes, so flooding is a big issue.
The net result of that, is that the barrier must mostly run along the course of the existing flood control levees - which can be a mile or more from the American Bank of the river. A lot of the floodplain South of the levees is rich farmland or fallow wilderness, but there is a non-trivial number of private homes and some businesses that would be constrained by being caught on the wrong side of a wall. Unlike the other border States, most of the border lands in Texas are privately owned, rather than managed by the Departments of the Interior (Bureaus of Land Management or Indian Affairs) or Defense.
Those private owners need to be accommodated (e.g. with keypad operated gates) or compensated for their losses, beyond just the 150 foot wide barrier path, which the Government plans to develop and operate. I believe that the Government will offer to buy owners out completely, but they only have to sell the 150 foot wide strip that the Government will condemn under eminent domain - they can negotiate additional compensation or accommodation for the constraints placed on their other property.
The final compensation amount can sometimes take a decade to finalize in court - but the Government can take ownership and build the next day in the meantime.
These geographic and legal issues means Texas has the most difficult and expensive places to build along the whole border (no plans to build in steep mountain areas). The massive FEMA Hurricane certified concrete levees that must form the foundation of the border barrier in the lower Rio Grande Valley drives the price up near $25 million per mile (As little as $4 million per mile in the rural flat desert). Beyond being the difficult and expensive miles, they are also the most important miles, where the most illegals cross into our Country.
This years funding was the main battle in the war to build an effective wall. The Presidents plan targets the most important miles first. The $8 billion that the President has obtained (despite the great wailing and gnashing of teeth), is enough to button up the Rio Grande Valley and the main border cities; where over 3/4 of current traffic now crosses. Everything after that great effort should be significantly easier, cheaper and faster to build.
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bump
This brings up a question: If there are any places where the wall has to be placed *north* of the actual border for a distance of, let's say two feet or more, then what is the legality of an MS-13 gang member's 9-month-pregnant girlfriend laying down on the Mexican side of the wall right up against the wall but actually in US territory, and begatting an Anchor Baby?