http://gallery.pictopia.com/providerasset/1/pictopia_logo.pnghttp://gallery.pictopia.com/providerasset/1/pictopia_logo.pnghttp://gallery.pictopia.com/natgeo/gallery/15524/2012-02-04T15:51:39Z2012-02-04T15:51:39Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953004/

A stark cross hangs at the border for an unknown migrant who sought prosperity in the U.S. but died in the crossing.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953004&size=128&m=1328399499.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953004&size=128&m=1328399499.0Tijuana, Mexicohttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953004/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2008-12-10T08:12:15Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952999/

An improvised wall of military surplus steel cuts a rusty slash toward the horizon. In Tijuana, where poverty is rising and half of all new residents live in squatter communities without clean water, the wall is hard to ignore: Houses push up close to the border. On the U.S. side, development is far removed from the barrier.

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Old Glory juts toward the Mexican border as if in warning. Unlike most barriers on the border, the nearly mile-long fence on a local rancher's land was built not by the U.S. government but by a private group, the Minuteman Civil Defense Corps, which opposes the influx of illegal immigrants. The group promises that if the government doesn't seal the border, it will.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953019&size=128&m=1189624579.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953019&size=128&m=1189624579.0Naco, Arizonahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953019/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-07-18T11:07:47Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953021/

Freight rolls a few feet north of Mexico on a line repeatedly hit by train robbers unfazed by border fences. Here, the easternmost man-made barrier on the international frontier ends abruptly near the Rio Grande.

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A metal wall and a concrete fence impassively bar illegal entry in a floodlit no-man's-land where Border Patrol agents keep close watch.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953008&size=128&m=1184782067.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953008&size=128&m=1184782067.0San Diego, Californiahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953008/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-07-18T11:07:47Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953018/

On the Arizona side of a vehicle barrier, Border Patrol agents have smoothed the sand with old tires so they can "cut sign"—track the footprints of migrants tempting fate on this remote desert route.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953018&size=128&m=1184782067.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953018&size=128&m=1184782067.0San Luis, Arizonahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953018/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-07-13T19:21:36Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952981/

The hills of California appear dreamlike beyond a section of steel mesh wall with a door that opens only for Border Patrol agents.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952981&size=128&m=1184379696.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952981&size=128&m=1184379696.0Otay Mesa, Californiahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952981/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-25T22:59:13Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953061/

East of Naco, a monument and a barbed-wire fence mark the U.S.-Mexico border. Formerly Mexican territory, the United States purchased southern reaches of Arizona and New Mexico from Mexico in 1853. Five years before that, at the end of the Mexican-American war, Mexico had ceded to the United States much of the territory that now makes up the southwestern U.S.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953061&size=128&m=1177567153.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953061&size=128&m=1177567153.0Barren Frontierhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953061/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-17T12:30:49Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953015/

The border wall winds through moonscape, following the demands of terrain rather than the political boundary that lies several hundred yards south.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953015&size=128&m=1176838249.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953015&size=128&m=1176838249.0Andrade, Californiahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953015/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-04T17:38:30Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953059/

Border Patrol agents in Nogales, Arizona, protect themselves with an old baseball backstop. Before they put it up, would-be border crossers (or helpers attempting to create a diversion) would toss rocks over the wall in the direction of the agents; now officers park behind it and monitor the border in safety.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953059&size=128&m=1175733510.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953059&size=128&m=1175733510.0Flagrant Foulhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953059/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-04T17:38:30Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953060/

Figures of Santa Muerte—Saint Death—face north near the border crossing in Agua Prieta, Mexico. The skull-faced object of veneration is not an actual saint of the Roman Catholic Church, but a folklore figure increasingly popular with those who live on the edge—drug runners, coyotes, smugglers.

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The grass is dying and the shade trees collapsing, but security lights are in full bloom on a former golf course now used for policing the border. Ironically, say some immigration experts, the increasing lockdown can backfire, frightening migrants from attempting the journey home and thus lengthening their stays in the U.S.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953011&size=128&m=1175733505.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:953011&size=128&m=1175733505.0Calexico, Californiahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/953011/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-04T17:38:24Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952990/

Barricades like those that bristled off Normandy beaches on D-Day now guard desert. They stop smugglers of drugs and migrants from driving across the border but let the endangered Sonoran pronghorn pass. Allusions to war are apt: In 2002, before the barriers were in place, drug cartel gunmen killed a U.S. park ranger here.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952990&size=128&m=1175733504.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952990&size=128&m=1175733504.0Organ Pipe Cactus National Monument, Arizonahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952990/In the Magazine/Past Issues/May 2007/May 2007 Border Walls2007-04-04T17:38:24Zhttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952985/

A surreal hedge of upended railway tracks, easily penetrated or bypassed by immigrants willing to get their feet wet, marks the western extent of the U.S.-Mexico border.

//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952985&size=128&m=1175733504.0//pictopia.com/perl/get_image?provider_id=318&ptp_photo_id=natgeo:952985&size=128&m=1175733504.0Border Field State Park, Californiahttp://gallery.pictopia.com/natgeo/gallery/15524/photo/952985/In the Magazine/Past Issues/May 2007/May 2007 Border Walls