Geographic Patterns and Profiling of Illegal Land Border Crossings D. Kim Rossmo Quint C. Thurman

Border Control  Geographic range  Porous nature  US national security  Significant challenge Rugged terrain of El Paso border

The Illegal Border Crossing “Arms Race” Ground sensor and UAV Fencing and electronic gate Trucks in Rio Grande canyon Inner tubes along the Rio Grande

Berlin Wall  10,315 days  August 1961 to November 1989  East / West Berlin border 27 miles  West Berlin border 96 miles  12-foot wall, 302 watch towers, 20 bunkers  192 deaths, 200 shooting injuries  5,000 escapes (3.4 per week)

US Border Patrol Sectors

Texas- Mexico Border  1,000 miles  52% of southern border  1,933 miles  50% federal land

Theoretical Perspective  Criminal behavior  Bounded rationality  Shaped by personal and environmental factors  Migration theory  Origin (push) factors  Destination (pull) factors)  Distance (effort, time, money)  Cost/benefit (risk/reward) analysis framework

Illegal Border Crossing Requirements  Trip origin  Border  Staging area  Crossing  Landing  Trip destination

Premise  Identify border crossing factors  Facilitating  Inhibiting  Determine features related to probability of illegal border movement  Environmental  Physical

US Border Patrol Data  2001 to 2004 (4 years)  1 to 1.6 million cases annually in the US  20 to 25% of these cases are in Texas  Laredo, McAllen, Del Rio, Marfa, and El Paso Sectors

 Dependent  Illegal Texas-Mexico land border crossings  Independent  Physical geography  Human geography Research Variables

Preliminary Focus Area  Del Rio Border Patrol Sector  Val Verde, Kinney, & Maverick Counties  111 Landmark Mile Markers (170 miles)

Physical Geography  Hydrography  Terrain  Vegetation  Temperature (day and night)

Hydrography  Types of features  Streams  Rivers  Lakes  Reservoirs  Data sources  US Census (USA)  INEGI (Mexico)

Terrain (USGS DEM)  Extent  All counties  Mexico overlap  Primary Output  Elevation  Slope  Aspect  Hillshade  Identification  Ravines  Gullies

Vegetation  Types of features  Brush  Crops  Parks  Woods  Data sources  TPWD (US)  INEGI (Mexico)

Temperature  Monthly normals  Minimum  Maximum  Annual normals  Mean

Human Geography Variables  Major transportation  Population density  Urban developments  Political region  Additional features

Major Transportation  Types  Airports  Railroads  Roads  Bridges  US data sources  US Census  TCEQ  Mexico data sources  GeoCommunity

Population Density & Urban Development  US data  2000 US Census  All counties  Mexico Data  1990 Census  Mexico

Del Rio Illegal Border Crossings

Del Rio Illegal Border Crossings (Cumulative %) G = 0.64 ID = 0.49

Del Rio Sector – All Illegal Entries , , , , , ,717

All Entries

Del Rio Sector – Criminal Entries

Criminal Entries

Density of Del Rio Sector Illegal Entries

Residence Country (Excluding Mexico)

US or Mexico State of Birth

Gender

Apprehension Age

Distance to United States Urban Areas

Distance to Mexico Urban Areas

Slope Least Cost Path  Cost-weighted distance (higher slope = greater cost)  Cost-weighted direction (least cost direction to source)  Least cost path (to rural highway segments)

Combined Slope Cost-Weighted Distance  Top 10 criminal disposition entry Landmark Mile Markers  Weighted by number of criminal disposition entries  323 total entries

Slope Cost Distance Analysis  Travel across terrain values is more difficult (higher “cost”)  Border areas with low slope cost values are attractive to illegal border crossers

Elevation Change Analysis  Border areas with higher elevation on the Mexico side are attractive to illegal border crossers  Elevation differentials allows for surveillance of US Border Patrol vehicles

Viewshed Analysis  The viewshed (line of sight) identifies all locations visible from a given point  Areas with low viewshed values are attractive to illegal border crossers due to low detection risk

Illegal Border Crosser Population Estimates  Official estimates: +10 to 50%  Line officer estimates: +100%

Capture-Recapture Analysis P S1S1 S2S2 O P = S 1 S 2 O ?

Scholarly Outcomes  Illegal movements  International migration  Spatial displacement  Natural and built factors  Microlevel environmental influences

Practical Products  US Border Patrol operations  Unidentified crossing points  Displacement anticipation  Criminal and drug interdiction  Counter-terrorism applications  Training