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 21, PORUM, OK 74455-0021
PO BOX 22, PORUM, OK 74455-0022
PO BOX 23, PORUM, OK 74455-0023
PO BOX 24, PORUM, OK 74455-0024
PO BOX 25, PORUM, OK 74455-0025
PO BOX 26, PORUM, OK 74455-0026
PO BOX 27, PORUM, OK 74455-0027
PO BOX 28, PORUM, OK 74455-0028
PO BOX 29, PORUM, OK 74455-0029
PO BOX 30, PORUM, OK 74455-0030
PO BOX 31, PORUM, OK 74455-0031
PO BOX 32, PORUM, OK 74455-0032
PO BOX 33, PORUM, OK 74455-0033
PO BOX 34, PORUM, OK 74455-0034
PO BOX 35, PORUM, OK 74455-0035
PO BOX 36, PORUM, OK 74455-0036
PO BOX 37, PORUM, OK 74455-0037
PO BOX 38, PORUM, OK 74455-0038
PO BOX 39, PORUM, OK 74455-0039
PO BOX 40, PORUM, OK 74455-0040
PO BOX 41, PORUM, OK 74455-0041
PO BOX 42, PORUM, OK 74455-0042
PO BOX 43, PORUM, OK 74455-0043
PO BOX 44, PORUM, OK 74455-0044
PO BOX 45, PORUM, OK 74455-0045
PO BOX 46, PORUM, OK 74455-0046
PO BOX 47, PORUM, OK 74455-0047
PO BOX 48, PORUM, OK 74455-0048
PO BOX 49, PORUM, OK 74455-0049
PO BOX 50, PORUM, OK 74455-0050
PO BOX 51, PORUM, OK 74455-0051
PO BOX 52, PORUM, OK 74455-0052
PO BOX 53, PORUM, OK 74455-0053
PO BOX 54, PORUM, OK 74455-0054
PO BOX 55, PORUM, OK 74455-0055
PO BOX 56, PORUM, OK 74455-0056
PO BOX 57, PORUM, OK 74455-0057
PO BOX 58, PORUM, OK 74455-0058
PO BOX 59, PORUM, OK 74455-0059
PO BOX 60, PORUM, OK 74455-0060
PO BOX 61, PORUM, OK 74455-0061
PO BOX 62, PORUM, OK 74455-0062
PO BOX 63, PORUM, OK 74455-0063
PO BOX 64, PORUM, OK 74455-0064
PO BOX 65, PORUM, OK 74455-0065
PO BOX 66, PORUM, OK 74455-0066
PO BOX 67, PORUM, OK 74455-0067
PO BOX 68, PORUM, OK 74455-0068
PO BOX 69, PORUM, OK 74455-0069
PO BOX 70, PORUM, OK 74455-0070
PO BOX 71, PORUM, OK 74455-0071
PO BOX 72, PORUM, OK 74455-0072
PO BOX 73, PORUM, OK 74455-0073
PO BOX 74, PORUM, OK 74455-0074
PO BOX 75, PORUM, OK 74455-0075
PO BOX 76, PORUM, OK 74455-0076
PO BOX 77, PORUM, OK 74455-0077
PO BOX 78, PORUM, OK 74455-0078
PO BOX 79, PORUM, OK 74455-0079
PO BOX 80, PORUM, OK 74455-0080
PO BOX 81, PORUM, OK 74455-0081
PO BOX 82, PORUM, OK 74455-0082
PO BOX 83, PORUM, OK 74455-0083
PO BOX 84, PORUM, OK 74455-0084
PO BOX 85, PORUM, OK 74455-0085
PO BOX 86, PORUM, OK 74455-0086
PO BOX 87, PORUM, OK 74455-0087
PO BOX 88, PORUM, OK 74455-0088
PO BOX 89, PORUM, OK 74455-0089
PO BOX 90, PORUM, OK 74455-0090
PO BOX 91, PORUM, OK 74455-0091
PO BOX 92, PORUM, OK 74455-0092
PO BOX 93, PORUM, OK 74455-0093
PO BOX 94, PORUM, OK 74455-0094
PO BOX 95, PORUM, OK 74455-0095
PO BOX 96, PORUM, OK 74455-0096
PO BOX 97, PORUM, OK 74455-0097
PO BOX 98, PORUM, OK 74455-0098
PO BOX 99, PORUM, OK 74455-0099
PO BOX 100, PORUM, OK 74455-0100
PO BOX 101, PORUM, OK 74455-0101
PO BOX 102, PORUM, OK 74455-0102
PO BOX 103, PORUM, OK 74455-0103
PO BOX 104, PORUM, OK 74455-0104
PO BOX 105, PORUM, OK 74455-0105
PO BOX 106, PORUM, OK 74455-0106
PO BOX 107, PORUM, OK 74455-0107
PO BOX 108, PORUM, OK 74455-0108
PO BOX 109, PORUM, OK 74455-0109
PO BOX 110, PORUM, OK 74455-0110
PO BOX 111, PORUM, OK 74455-0111
PO BOX 112, PORUM, OK 74455-0112
PO BOX 113, PORUM, OK 74455-0113
PO BOX 114, PORUM, OK 74455-0114
PO BOX 115, PORUM, OK 74455-0115
PO BOX 116, PORUM, OK 74455-0116
PO BOX 117, PORUM, OK 74455-0117
PO BOX 118, PORUM, OK 74455-0118
PO BOX 119, PORUM, OK 74455-0119
PO BOX 120, PORUM, OK 74455-0120
PO BOX 121, PORUM, OK 74455-0121
PO BOX 122, PORUM, OK 74455-0122
PO BOX 123, PORUM, OK 74455-0123
PO BOX 124, PORUM, OK 74455-0124
PO BOX 125, PORUM, OK 74455-0125
PO BOX 126, PORUM, OK 74455-0126
PO BOX 127, PORUM, OK 74455-0127
PO BOX 128, PORUM, OK 74455-0128
PO BOX 129, PORUM, OK 74455-0129
PO BOX 130, PORUM, OK 74455-0130
PO BOX 131, PORUM, OK 74455-0131
PO BOX 132, PORUM, OK 74455-0132
PO BOX 133, PORUM, OK 74455-0133
PO BOX 134, PORUM, OK 74455-0134
PO BOX 135, PORUM, OK 74455-0135
PO BOX 136, PORUM, OK 74455-0136
PO BOX 137, PORUM, OK 74455-0137
PO BOX 138, PORUM, OK 74455-0138
PO BOX 139, PORUM, OK 74455-0139
PO BOX 140, PORUM, OK 74455-0140
PO BOX 141, PORUM, OK 74455-0141
PO BOX 142, PORUM, OK 74455-0142
PO BOX 143, PORUM, OK 74455-0143
PO BOX 144, PORUM, OK 74455-0144
PO BOX 145, PORUM, OK 74455-0145
PO BOX 146, PORUM, OK 74455-0146
PO BOX 147, PORUM, OK 74455-0147
PO BOX 148, PORUM, OK 74455-0148
PO BOX 149, PORUM, OK 74455-0149
PO BOX 150, PORUM, OK 74455-0150
PO BOX 151, PORUM, OK 74455-0151
PO BOX 152, PORUM, OK 74455-0152
PO BOX 153, PORUM, OK 74455-0153
PO BOX 154, PORUM, OK 74455-0154
PO BOX 155, PORUM, OK 74455-0155
PO BOX 156, PORUM, OK 74455-0156
PO BOX 157, PORUM, OK 74455-0157
PO BOX 158, PORUM, OK 74455-0158
PO BOX 159, PORUM, OK 74455-0159
PO BOX 160, PORUM, OK 74455-0160
PO BOX 161, PORUM, OK 74455-0161
PO BOX 162, PORUM, OK 74455-0162
PO BOX 163, PORUM, OK 74455-0163
PO BOX 164, PORUM, OK 74455-0164
PO BOX 165, PORUM, OK 74455-0165
PO BOX 166, PORUM, OK 74455-0166
PO BOX 167, PORUM, OK 74455-0167
PO BOX 168, PORUM, OK 74455-0168
PO BOX 169, PORUM, OK 74455-0169
PO BOX 170, PORUM, OK 74455-0170
PO BOX 171, PORUM, OK 74455-0171
PO BOX 172, PORUM, OK 74455-0172
PO BOX 173, PORUM, OK 74455-0173
PO BOX 174, PORUM, OK 74455-0174
PO BOX 175, PORUM, OK 74455-0175
PO BOX 176, PORUM, OK 74455-0176
PO BOX 177, PORUM, OK 74455-0177
PO BOX 178, PORUM, OK 74455-0178
PO BOX 179, PORUM, OK 74455-0179
PO BOX 180, PORUM, OK 74455-0180
PO BOX 181, PORUM, OK 74455-0181
PO BOX 182, PORUM, OK 74455-0182
PO BOX 183, PORUM, OK 74455-0183
PO BOX 184, PORUM, OK 74455-0184
PO BOX 185, PORUM, OK 74455-0185
PO BOX 186, PORUM, OK 74455-0186
PO BOX 187, PORUM, OK 74455-0187
PO BOX 188, PORUM, OK 74455-0188
PO BOX 189, PORUM, OK 74455-0189
PO BOX 190, PORUM, OK 74455-0190
PO BOX 191, PORUM, OK 74455-0191
PO BOX 192, PORUM, OK 74455-0192
PO BOX 193, PORUM, OK 74455-0193
PO BOX 194, PORUM, OK 74455-0194
PO BOX 195, PORUM, OK 74455-0195
PO BOX 196, PORUM, OK 74455-0196
PO BOX 197, PORUM, OK 74455-0197
PO BOX 198, PORUM, OK 74455-0198
PO BOX 199, PORUM, OK 74455-0199
PO BOX 200, PORUM, OK 74455-0200
PO BOX 201, PORUM, OK 74455-0201
PO BOX 202, PORUM, OK 74455-0202
PO BOX 203, PORUM, OK 74455-0203
PO BOX 204, PORUM, OK 74455-0204
PO BOX 205, PORUM, OK 74455-0205
PO BOX 206, PORUM, OK 74455-0206
PO BOX 207, PORUM, OK 74455-0207
PO BOX 208, PORUM, OK 74455-0208
PO BOX 209, PORUM, OK 74455-0209
PO BOX 210, PORUM, OK 74455-0210
PO BOX 211, PORUM, OK 74455-0211
PO BOX 212, PORUM, OK 74455-0212
PO BOX 213, PORUM, OK 74455-0213
PO BOX 214, PORUM, OK 74455-0214
PO BOX 215, PORUM, OK 74455-0215
PO BOX 216, PORUM, OK 74455-0216
PO BOX 217, PORUM, OK 74455-0217
PO BOX 218, PORUM, OK 74455-0218
PO BOX 219, PORUM, OK 74455-0219
PO BOX 220, PORUM, OK 74455-0220
PO BOX 221, PORUM, OK 74455-0221