How many U.S. states border Mexico?
4
13
13
13
13
13
5
13
5
13
5
10
13
7
5
10
13
7
14
5
10
13
7
14
5
9
10
13
2
7
14
5
9
10
13
2
7
12
14
5
9
10
4
13
8
2
7
12
14
5
9
10
4
13
8
2
7
21
12
14
5
9
10
4
13
8
2
7
21
12
14
5
9
10
4
3
1
11
13
8
2
7
21
12
14
5
9
10
4
3
1
11
13
8
2
7
21
12
6
14
5
9
10
31
4
3
1
11
27
15
13
8
2
7
21
12
6
14
5
9
10
31
4
3
1
11
27
15
13
8
2
7
20
21
12
6
14
5
9
10
31
4
3
1
11
27
15
13
8
2
7
20
21
12
6
14
5
9
29
10
31
4
3
1
11
27
15
8
2
7
20
21
12
6
14
5
9
13 states
29
10
31
4
3
1
11
27
15
8
2
7
20
21
12
34
6
14
5
9
29
10
31