The web site of the International Boundary and Water Commission (US Section)
invites questions by e-mail from members of the public to the Public Affairs
Office at the IWBC headquarters in El Paso. Therefore, I have sent them the
question below. This is not meant to compete with Mr. Nadybal's proposed
inquiry at Washington, but the IWBC's presence there is only a "Special
Assistant" who is housed within the State Department's Office of Mexican
Affairs. Perhaps he's thinking of a different agency, the International
Boundary Commission (US Section), which has its headquarters in Washington, but
it only deals with the Canadian border.

++++++++++++++++++++++++++++++++++++

Hello,

While I am a resident of Louisiana, I own property within sight of the border
near Eagle Pass, Texas. I have a greater-than-average interest in the US/Mexico
boundary.

I have some questions regarding the boundary monuments on bridges. I am aware
that bridges on the Rio Grande section of the boundary have upon them a boundary
monument placed by the IWBC or one of it predecessors. I have noted several
examples where the Rio Grande has moved by accretion such that it is no longer
under the monuments on the bridges. I know that (in the absence of treaty
provisions to the contrary) it is a general principal of boundary study that
water boundaries move with accretion of the waterbodies that constitute the
boundary.

The railroad bridge at Eagle Pass/Piedras Negras makes a prime example. The
bridge was built in 1922, and the monument on the bridge stands beside the steel
superstructure on a stone masonry bridge pier that must have been in the middle
of the river at that time. Since then, however, the river has moved by
accretion significantly southward. The bridge pier upon which the monument sits
is high and dry, perhaps fifty feet or more from the north margin of the river
at its normal stage. The area is easily accessible by road and appears to be
something of a lovers' lane. It is possible to drive a motor vehicle all the
way around the base of the pier upon which the boundary monument sits.

My questions related to this and other similar examples are these:

1. Does the placement of an IWBC monument on a port-of-entry bridge permanently
fix the boundary at that point on the bridge structure, trumping the effects of
any future accretion of the river; OR is the monument on the bridge merely a
curious relict of where the boundary once was when the bridge was built?

2. If the placement of a monument on a bridge permanently fixes the boundary on
the bridge structure, then under which sovereignty is the dry land on one side
of the river that is directly beneath the opposite nation's part of the bridge?

3. If the boundary deviates from the moveable middle of the river and extends
one way or the other to a monument permanently fixed on a bridge, thus creating
a finger of one nation into the other, how wide is that finger? Is it only as
wide as the physical structure of the bridge, or is it as wide as the respective
railroad or highway's right-of-way?

4. Are there actually any answers to such questions as these, or are they
resolved only case-by-case as the need arises?

I thank you for your attention and for whatever answers you can provide.

Lowell G. McManus
Leesville, Louisiana, USA