A PO BOX number can be less than or more than four digit. For post office boxes, the general rule is that each box has its own ZIP+4 code.
The last four digit is often one of the following:
1. Zero plus the last three digits of the box number (eg. PO BOX 1001, Los Angeles CA 90001-0001).
2. The last four digits of the box number (eg. PO BOX 9991, Twin Peaks CA 92391-9991).
3. If the box number is less than four digits, enough zeros prepended to the front of the box number to produce a four-digit number(eg. PO BOX 1, Shreveport LA 71161-0001).
However, there is no uniform rule, the zip code plus four is for reference only, the ZIP+4 code must be looked up individually for each box in the USPS offical website.
PO BOX 1, SAN MARCOS, CA 92079-0001
PO BOX 2, SAN MARCOS, CA 92079-0002
PO BOX 3, SAN MARCOS, CA 92079-0003
PO BOX 4, SAN MARCOS, CA 92079-0004
PO BOX 5, SAN MARCOS, CA 92079-0005
PO BOX 6, SAN MARCOS, CA 92079-0006
PO BOX 7, SAN MARCOS, CA 92079-0007
PO BOX 8, SAN MARCOS, CA 92079-0008
PO BOX 9, SAN MARCOS, CA 92079-0009
PO BOX 10, SAN MARCOS, CA 92079-0010
PO BOX 11, SAN MARCOS, CA 92079-0011
PO BOX 12, SAN MARCOS, CA 92079-0012
PO BOX 13, SAN MARCOS, CA 92079-0013
PO BOX 14, SAN MARCOS, CA 92079-0014
PO BOX 15, SAN MARCOS, CA 92079-0015
PO BOX 16, SAN MARCOS, CA 92079-0016
PO BOX 17, SAN MARCOS, CA 92079-0017
PO BOX 18, SAN MARCOS, CA 92079-0018
PO BOX 19, SAN MARCOS, CA 92079-0019
PO BOX 20, SAN MARCOS, CA 92079-0020
PO BOX 21, SAN MARCOS, CA 92079-0021
PO BOX 22, SAN MARCOS, CA 92079-0022
PO BOX 23, SAN MARCOS, CA 92079-0023
PO BOX 24, SAN MARCOS, CA 92079-0024
PO BOX 25, SAN MARCOS, CA 92079-0025
PO BOX 26, SAN MARCOS, CA 92079-0026
PO BOX 27, SAN MARCOS, CA 92079-0027
PO BOX 28, SAN MARCOS, CA 92079-0028
PO BOX 29, SAN MARCOS, CA 92079-0029
PO BOX 30, SAN MARCOS, CA 92079-0030
PO BOX 31, SAN MARCOS, CA 92079-0031
PO BOX 32, SAN MARCOS, CA 92079-0032
PO BOX 33, SAN MARCOS, CA 92079-0033
PO BOX 34, SAN MARCOS, CA 92079-0034
PO BOX 35, SAN MARCOS, CA 92079-0035
PO BOX 36, SAN MARCOS, CA 92079-0036
PO BOX 37, SAN MARCOS, CA 92079-0037
PO BOX 38, SAN MARCOS, CA 92079-0038
PO BOX 39, SAN MARCOS, CA 92079-0039
PO BOX 40, SAN MARCOS, CA 92079-0040
PO BOX 41, SAN MARCOS, CA 92079-0041
PO BOX 42, SAN MARCOS, CA 92079-0042
PO BOX 43, SAN MARCOS, CA 92079-0043
PO BOX 44, SAN MARCOS, CA 92079-0044
PO BOX 45, SAN MARCOS, CA 92079-0045
PO BOX 46, SAN MARCOS, CA 92079-0046
PO BOX 47, SAN MARCOS, CA 92079-0047
PO BOX 48, SAN MARCOS, CA 92079-0048
PO BOX 49, SAN MARCOS, CA 92079-0049
PO BOX 50, SAN MARCOS, CA 92079-0050
PO BOX 51, SAN MARCOS, CA 92079-0051
PO BOX 52, SAN MARCOS, CA 92079-0052
PO BOX 53, SAN MARCOS, CA 92079-0053
PO BOX 54, SAN MARCOS, CA 92079-0054
PO BOX 55, SAN MARCOS, CA 92079-0055
PO BOX 56, SAN MARCOS, CA 92079-0056
PO BOX 57, SAN MARCOS, CA 92079-0057
PO BOX 58, SAN MARCOS, CA 92079-0058
PO BOX 59, SAN MARCOS, CA 92079-0059
PO BOX 60, SAN MARCOS, CA 92079-0060
PO BOX 61, SAN MARCOS, CA 92079-0061
PO BOX 62, SAN MARCOS, CA 92079-0062
PO BOX 63, SAN MARCOS, CA 92079-0063
PO BOX 64, SAN MARCOS, CA 92079-0064
PO BOX 65, SAN MARCOS, CA 92079-0065
PO BOX 66, SAN MARCOS, CA 92079-0066
PO BOX 67, SAN MARCOS, CA 92079-0067
PO BOX 68, SAN MARCOS, CA 92079-0068
PO BOX 69, SAN MARCOS, CA 92079-0069
PO BOX 70, SAN MARCOS, CA 92079-0070
PO BOX 71, SAN MARCOS, CA 92079-0071
PO BOX 72, SAN MARCOS, CA 92079-0072
PO BOX 73, SAN MARCOS, CA 92079-0073
PO BOX 74, SAN MARCOS, CA 92079-0074
PO BOX 75, SAN MARCOS, CA 92079-0075
PO BOX 76, SAN MARCOS, CA 92079-0076
PO BOX 77, SAN MARCOS, CA 92079-0077
PO BOX 78, SAN MARCOS, CA 92079-0078
PO BOX 79, SAN MARCOS, CA 92079-0079
PO BOX 80, SAN MARCOS, CA 92079-0080
PO BOX 81, SAN MARCOS, CA 92079-0081
PO BOX 82, SAN MARCOS, CA 92079-0082
PO BOX 83, SAN MARCOS, CA 92079-0083
PO BOX 84, SAN MARCOS, CA 92079-0084
PO BOX 85, SAN MARCOS, CA 92079-0085
PO BOX 86, SAN MARCOS, CA 92079-0086
PO BOX 87, SAN MARCOS, CA 92079-0087
PO BOX 88, SAN MARCOS, CA 92079-0088
PO BOX 89, SAN MARCOS, CA 92079-0089
PO BOX 90, SAN MARCOS, CA 92079-0090
PO BOX 91, SAN MARCOS, CA 92079-0091
PO BOX 92, SAN MARCOS, CA 92079-0092
PO BOX 93, SAN MARCOS, CA 92079-0093
PO BOX 94, SAN MARCOS, CA 92079-0094
PO BOX 95, SAN MARCOS, CA 92079-0095
PO BOX 96, SAN MARCOS, CA 92079-0096
PO BOX 97, SAN MARCOS, CA 92079-0097
PO BOX 98, SAN MARCOS, CA 92079-0098
PO BOX 99, SAN MARCOS, CA 92079-0099
PO BOX 100, SAN MARCOS, CA 92079-0100
PO BOX 101, SAN MARCOS, CA 92079-0101
PO BOX 102, SAN MARCOS, CA 92079-0102
PO BOX 103, SAN MARCOS, CA 92079-0103
PO BOX 104, SAN MARCOS, CA 92079-0104
PO BOX 105, SAN MARCOS, CA 92079-0105
PO BOX 106, SAN MARCOS, CA 92079-0106
PO BOX 107, SAN MARCOS, CA 92079-0107
PO BOX 108, SAN MARCOS, CA 92079-0108
PO BOX 109, SAN MARCOS, CA 92079-0109
PO BOX 110, SAN MARCOS, CA 92079-0110
PO BOX 111, SAN MARCOS, CA 92079-0111
PO BOX 112, SAN MARCOS, CA 92079-0112
PO BOX 113, SAN MARCOS, CA 92079-0113
PO BOX 114, SAN MARCOS, CA 92079-0114
PO BOX 115, SAN MARCOS, CA 92079-0115
PO BOX 116, SAN MARCOS, CA 92079-0116
PO BOX 117, SAN MARCOS, CA 92079-0117
PO BOX 118, SAN MARCOS, CA 92079-0118
PO BOX 119, SAN MARCOS, CA 92079-0119
PO BOX 120, SAN MARCOS, CA 92079-0120
PO BOX 121, SAN MARCOS, CA 92079-0121
PO BOX 122, SAN MARCOS, CA 92079-0122
PO BOX 123, SAN MARCOS, CA 92079-0123
PO BOX 124, SAN MARCOS, CA 92079-0124
PO BOX 125, SAN MARCOS, CA 92079-0125
PO BOX 126, SAN MARCOS, CA 92079-0126
PO BOX 127, SAN MARCOS, CA 92079-0127
PO BOX 128, SAN MARCOS, CA 92079-0128
PO BOX 129, SAN MARCOS, CA 92079-0129
PO BOX 130, SAN MARCOS, CA 92079-0130
PO BOX 131, SAN MARCOS, CA 92079-0131
PO BOX 132, SAN MARCOS, CA 92079-0132
PO BOX 133, SAN MARCOS, CA 92079-0133
PO BOX 134, SAN MARCOS, CA 92079-0134
PO BOX 135, SAN MARCOS, CA 92079-0135
PO BOX 136, SAN MARCOS, CA 92079-0136
PO BOX 137, SAN MARCOS, CA 92079-0137
PO BOX 138, SAN MARCOS, CA 92079-0138
PO BOX 139, SAN MARCOS, CA 92079-0139
PO BOX 140, SAN MARCOS, CA 92079-0140
PO BOX 141, SAN MARCOS, CA 92079-0141
PO BOX 142, SAN MARCOS, CA 92079-0142
PO BOX 143, SAN MARCOS, CA 92079-0143
PO BOX 144, SAN MARCOS, CA 92079-0144
PO BOX 145, SAN MARCOS, CA 92079-0145
PO BOX 146, SAN MARCOS, CA 92079-0146
PO BOX 147, SAN MARCOS, CA 92079-0147
PO BOX 148, SAN MARCOS, CA 92079-0148
PO BOX 149, SAN MARCOS, CA 92079-0149
PO BOX 150, SAN MARCOS, CA 92079-0150
PO BOX 151, SAN MARCOS, CA 92079-0151
PO BOX 152, SAN MARCOS, CA 92079-0152
PO BOX 153, SAN MARCOS, CA 92079-0153
PO BOX 154, SAN MARCOS, CA 92079-0154
PO BOX 155, SAN MARCOS, CA 92079-0155
PO BOX 156, SAN MARCOS, CA 92079-0156
PO BOX 157, SAN MARCOS, CA 92079-0157
PO BOX 158, SAN MARCOS, CA 92079-0158
PO BOX 159, SAN MARCOS, CA 92079-0159
PO BOX 160, SAN MARCOS, CA 92079-0160
PO BOX 161, SAN MARCOS, CA 92079-0161
PO BOX 162, SAN MARCOS, CA 92079-0162
PO BOX 163, SAN MARCOS, CA 92079-0163
PO BOX 164, SAN MARCOS, CA 92079-0164
PO BOX 165, SAN MARCOS, CA 92079-0165
PO BOX 166, SAN MARCOS, CA 92079-0166
PO BOX 167, SAN MARCOS, CA 92079-0167
PO BOX 168, SAN MARCOS, CA 92079-0168
PO BOX 169, SAN MARCOS, CA 92079-0169
PO BOX 170, SAN MARCOS, CA 92079-0170
PO BOX 171, SAN MARCOS, CA 92079-0171
PO BOX 172, SAN MARCOS, CA 92079-0172
PO BOX 173, SAN MARCOS, CA 92079-0173
PO BOX 174, SAN MARCOS, CA 92079-0174
PO BOX 175, SAN MARCOS, CA 92079-0175
PO BOX 176, SAN MARCOS, CA 92079-0176
PO BOX 177, SAN MARCOS, CA 92079-0177
PO BOX 178, SAN MARCOS, CA 92079-0178
PO BOX 179, SAN MARCOS, CA 92079-0179
PO BOX 180, SAN MARCOS, CA 92079-0180
PO BOX 181, SAN MARCOS, CA 92079-0181
PO BOX 182, SAN MARCOS, CA 92079-0182
PO BOX 183, SAN MARCOS, CA 92079-0183
PO BOX 184, SAN MARCOS, CA 92079-0184
PO BOX 185, SAN MARCOS, CA 92079-0185
PO BOX 186, SAN MARCOS, CA 92079-0186
PO BOX 187, SAN MARCOS, CA 92079-0187
PO BOX 188, SAN MARCOS, CA 92079-0188
PO BOX 189, SAN MARCOS, CA 92079-0189
PO BOX 190, SAN MARCOS, CA 92079-0190
PO BOX 191, SAN MARCOS, CA 92079-0191
PO BOX 192, SAN MARCOS, CA 92079-0192
PO BOX 193, SAN MARCOS, CA 92079-0193
PO BOX 194, SAN MARCOS, CA 92079-0194
PO BOX 195, SAN MARCOS, CA 92079-0195
PO BOX 196, SAN MARCOS, CA 92079-0196
PO BOX 197, SAN MARCOS, CA 92079-0197
PO BOX 198, SAN MARCOS, CA 92079-0198
PO BOX 199, SAN MARCOS, CA 92079-0199
PO BOX 200, SAN MARCOS, CA 92079-0200
PO BOX 201, SAN MARCOS, CA 92079-0201
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