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
Fencing and electronic gate
Inner tubes along the Rio Grande
The Illegal Border Crossing “Arms Race”
Trucks in Rio Grande canyon
Ground sensor and UAV
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
TexasMexico
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
Research Variables


Dependent
 Illegal Texas-Mexico land border crossings
Independent
 Physical geography
 Human geography
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
October 1, 2000 - August 17, 2004
All Entries
18,000
16,000
14,000
10,000
8,000
6,000
4,000
2,000
Landmark Mile Marker
(North to South Order)
M-45
M-41
M-37
M-33
M-29
M-25
M-21
M-17
M-13
M-09 A
M-6
M-2.5
K-7
K-3
V-47
V-43
V-41
V-39
V-36
V-32
V-29
V-25
V-21
V-17
V-13
V-9
V-5
0
V-1
Entries
12,000
October 1, 2000 - August 17, 2004
Criminal Disposition Entries
100
90
80
60
50
40
30
20
10
Landmark Mile Marker
(North to South Order)
M-45
M-41
M-37
M-33
M-29
M-25
M-21
M-17
M-13
M-09 A
M-6
M-2.5
K-7
K-3
V-47
V-43
V-41
V-39
V-36
V-32
V-29
V-25
V-21
V-17
V-13
V-9
V-5
0
V-1
Entries
70
Del Rio Illegal Border Crossings
Del Rio Illegal Border Crossings
4,000
Crossings
3,000
2,000
1,000
0
1
21
41
61
Landmarks
81
101
Del RioDelIllegal
Border Crossings
Rio Illegal Border Crossings,
Cumulative Percentage
(Cumulative
%)
100.0%
90.0%
80.0%
Crossings
70.0%
60.0%
50.0%
40.0%
G = 0.64
ID = 0.49
30.0%
20.0%
10.0%
0.0%
1
21
41
61
Landmarks
81
101
Del Rio Sector –
All Illegal Entries
2000
2001
2002
2003
2004
2000-04
14,520
86,974
61,974
53,744
37,534
254,717
All Entries
Del Rio Sector –
Criminal Entries
2000
2001
2002
2003
2004
2000-04
5
129
289
162
585
Criminal Entries
Density of
Del Rio Sector
Illegal Entries
Entries by Month
All Entries
45,000
40,000
Entries
35,000
30,000
25,000
20,000
15,000
10,000
5,000
0
Ja
n
ry
a
u
Fe
y
ar
u
br
c
ar
M
h
ril
p
A
ay
M
n
Ju
e
t
ly
u
J
A
us
g
u
S
Month
t
ep
be
m
e
r
ct
O
e
ob
r
N
e
ov
m
r
be
D
em
c
e
r
be
Month
D
be
r
er
r
t
be
r
m
m
ov
e
ob
m
be
O
ct
pt
e
ec
e
N
Se
gu
s
ly
ne
Ju
Ju
M
ay
ril
ch
Ap
M
ar
ry
ar
y
br
ua
nu
Au
Fe
Ja
Entries
Entries by Month
Criminal Disposition Entries
80
70
60
50
40
30
20
10
0
Entries by Day of Month
All Entries
10,000
9,000
8,000
Entries
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
1
3
5
7
9
11
13
15
17
19
Day of Month
21
23
25
27
29
31
Entries by Day of Week
All Entries
Sunday
40,000
38,000
Saturday
Monday
36,000
34,000
32,000
30,000
Friday
Tuesday
Thursday
Wednesday
Entries by Day of Week
Criminal Disposition Entries
Sunday
110
100
90
Saturday
Monday
80
70
60
50
40
Friday
Tuesday
Thursday
Wednesday
Time of Entry - All Entries
0:00
23:00
16000
1:00
22:00
2:00
21:00
3:00
12000
20:00
4:00
8000
19:00
5:00
18:00
4000
6:00
17:00
7:00
16:00
8:00
15:00
9:00
14:00
10:00
13:00
11:00
12:00
Time of Entry - Criminal Disposition Entries
0:00
23:00
50
1:00
45
22:00
2:00
40
21:00
3:00
35
30
20:00
4:00
25
20
15
19:00
5:00
10
5
18:00
0
6:00
17:00
7:00
16:00
8:00
15:00
9:00
14:00
10:00
13:00
11:00
12:00
Residence Country (Excluding Mexico)
Residence Country (w/o Mexico)
All Entries
10000
HONDURAS
8237
Residence Country (w/o Mexico)
Criminal Disposition Entries
8000
HONDURAS
18
16
2000
BRAZIL
141
NICARAGUA
204
12
EL SALVADOR
7
8
C
H
IL
LO E
M
B
IA
C
U
EC BA
U
EL
A
DO
SA
LV
R
AD
O
R
ET
H
G
IO
U
P
AT
EM IA
AL
A
IS
R
M
A
A
CE EL
D
O
N
IA
N
IG
ER
IA
PA
N
AM
SO
A
M
AL
IA
S
VE UD
A
N
EZ N
U
EL
A
BRAZIL
4
4
O
GUATEM ALA
2
C
NICARAGUA
1
H
IL
LO E
M
B
IA
C
U
EC BA
U
EL
A
DO
SA
LV
R
AD
O
R
ET
H
G
I
O
U
PI
AT
EM A
AL
A
IS
R
M
A
A
CE EL
D
O
N
IA
N
IG
ER
IA
PA
N
AM
SO
A
M
AL
IA
S
VE UD
A
N
EZ N
U
EL
A
O
C
ZI
L
A
BR
IA
BE
AN
Country
LI
ZE
0
AL
B
ZI
L
A
LI
ZE
BR
AN
BE
IA
0
C
ALBANIA
26
GUATEM ALA
1398
Entries
EL SALVADOR
3459
4000
AL
B
Entries
20
6000
Country
US or Mexico State of Birth
US or Mexico State of Birth
All Entries
125
GUANAJUATO
124
50000
GUANAJUATO
42862
100
OTHER
COUNTRY
14350
COAHUILA
20516
20000
DURANGO HIDALGO
4778
3779
QUERETARO
5048
75
M EXICO
29
ZACATECAS
5721
25
VERACRUZ
5707
DURANGO
16
M ICHOACAN
18
VERACRUZ
48 OTHER
COUNTRY
35
TEXAS
37 ZACATECAS
30
QUERETARO
15
0
State
AS
C
A
LI
E
AL NTE
IF
S
O
C
R
D
H
N
IS
TR IHU IA
AH
IT
O
U
A
FE
D
E
G
R
U
ER AL
R
E
IN RO
D
LO IAN
A
U
IS
M
IC IAN
A
H
O
AC
A
N
AY N
N
AR
U
EV
IT
O
LE
SA
O
PU
N
N
LU E B
LA
IS
PO
TA TO
BA S I
SC
O
TE
XA
W
O
TH IS C S
O
E
N
R
S
C
IN
O
U
N
TR
Y
LI
E
AL NTE
IF
S
O
C
R
D
H
N
IS
TR IHU IA
AH
IT
O
U
A
FE
G DE R
U
ER AL
R
E
IN RO
D
I
LO AN
A
U
IS
M
I
A
IC
N
A
H
O
AC
A
N
AY N
N
AR
U
EV
IT
O
LE
SA
PU ON
N
LU E B
LA
IS
PO
TA TO
BA S I
SC
O
TE
X
W
A
O
TH IS C S
O
E
N
R
S
C
IN
O
U
N
TR
Y
A
AG
U
C
AS
C
U
SAN
LUIS
POTOSI
44
50
0
AG
COAHUILA
89
C
10000
M EXICO
8358
SAN
LUIS
POTOSI
8658
Entries
Entries
40000
30000
US or Mexico State of Birth
Criminal Disposition Entries
State
Gender
Gender
All Entries
240000
Gender
Criminal Disposition Entries
200000
600
500
120000
400
80000
Entries
Entries
160000
40000
300
200
0
FEMALE
MALE
Gender
UNKNOWN
100
0
FEMALE
MALE
Gender
UNKNOWN
Apprehension Age
Apprehension Age
All Entries
16000
14000
Apprehension Age
Criminal Disposition Entries
10000
8000
40
6000
35
4000
30
Entries
Entries
12000
2000
0
1
5
25
20
9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93
Age
15
10
5
0
1
5
9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93
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
O
500
Number
400
?
S2
S1
300
200
100
0
0
1
2
3
Samples
4
5
6
P = S1S2
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