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, MILFORD, CT 06460-0021
PO BOX 22, MILFORD, CT 06460-0022
PO BOX 23, MILFORD, CT 06460-0023
PO BOX 24, MILFORD, CT 06460-0024
PO BOX 25, MILFORD, CT 06460-0025
PO BOX 26, MILFORD, CT 06460-0026
PO BOX 27, MILFORD, CT 06460-0027
PO BOX 28, MILFORD, CT 06460-0028
PO BOX 29, MILFORD, CT 06460-0029
PO BOX 30, MILFORD, CT 06460-0030
PO BOX 31, MILFORD, CT 06460-0031
PO BOX 32, MILFORD, CT 06460-0032
PO BOX 33, MILFORD, CT 06460-0033
PO BOX 34, MILFORD, CT 06460-0034
PO BOX 35, MILFORD, CT 06460-0035
PO BOX 36, MILFORD, CT 06460-0036
PO BOX 37, MILFORD, CT 06460-0037
PO BOX 38, MILFORD, CT 06460-0038
PO BOX 39, MILFORD, CT 06460-0039
PO BOX 40, MILFORD, CT 06460-0040
PO BOX 41, MILFORD, CT 06460-0041
PO BOX 42, MILFORD, CT 06460-0042
PO BOX 43, MILFORD, CT 06460-0043
PO BOX 44, MILFORD, CT 06460-0044
PO BOX 45, MILFORD, CT 06460-0045
PO BOX 46, MILFORD, CT 06460-0046
PO BOX 47, MILFORD, CT 06460-0047
PO BOX 48, MILFORD, CT 06460-0048
PO BOX 49, MILFORD, CT 06460-0049
PO BOX 50, MILFORD, CT 06460-0050
PO BOX 51, MILFORD, CT 06460-0051
PO BOX 52, MILFORD, CT 06460-0052
PO BOX 53, MILFORD, CT 06460-0053
PO BOX 54, MILFORD, CT 06460-0054
PO BOX 55, MILFORD, CT 06460-0055
PO BOX 56, MILFORD, CT 06460-0056
PO BOX 57, MILFORD, CT 06460-0057
PO BOX 58, MILFORD, CT 06460-0058
PO BOX 59, MILFORD, CT 06460-0059
PO BOX 60, MILFORD, CT 06460-0060
PO BOX 61, MILFORD, CT 06460-0061
PO BOX 62, MILFORD, CT 06460-0062
PO BOX 63, MILFORD, CT 06460-0063
PO BOX 64, MILFORD, CT 06460-0064
PO BOX 65, MILFORD, CT 06460-0065
PO BOX 66, MILFORD, CT 06460-0066
PO BOX 67, MILFORD, CT 06460-0067
PO BOX 68, MILFORD, CT 06460-0068
PO BOX 69, MILFORD, CT 06460-0069
PO BOX 70, MILFORD, CT 06460-0070
PO BOX 71, MILFORD, CT 06460-0071
PO BOX 72, MILFORD, CT 06460-0072
PO BOX 73, MILFORD, CT 06460-0073
PO BOX 74, MILFORD, CT 06460-0074
PO BOX 75, MILFORD, CT 06460-0075
PO BOX 76, MILFORD, CT 06460-0076
PO BOX 77, MILFORD, CT 06460-0077
PO BOX 78, MILFORD, CT 06460-0078
PO BOX 79, MILFORD, CT 06460-0079
PO BOX 80, MILFORD, CT 06460-0080
PO BOX 81, MILFORD, CT 06460-0081
PO BOX 82, MILFORD, CT 06460-0082
PO BOX 83, MILFORD, CT 06460-0083
PO BOX 84, MILFORD, CT 06460-0084
PO BOX 85, MILFORD, CT 06460-0085
PO BOX 86, MILFORD, CT 06460-0086
PO BOX 87, MILFORD, CT 06460-0087
PO BOX 88, MILFORD, CT 06460-0088
PO BOX 89, MILFORD, CT 06460-0089
PO BOX 90, MILFORD, CT 06460-0090
PO BOX 91, MILFORD, CT 06460-0091
PO BOX 92, MILFORD, CT 06460-0092
PO BOX 93, MILFORD, CT 06460-0093
PO BOX 94, MILFORD, CT 06460-0094
PO BOX 95, MILFORD, CT 06460-0095
PO BOX 96, MILFORD, CT 06460-0096
PO BOX 97, MILFORD, CT 06460-0097
PO BOX 98, MILFORD, CT 06460-0098
PO BOX 99, MILFORD, CT 06460-0099
PO BOX 100, MILFORD, CT 06460-0100
PO BOX 101, MILFORD, CT 06460-0101
PO BOX 102, MILFORD, CT 06460-0102
PO BOX 103, MILFORD, CT 06460-0103
PO BOX 104, MILFORD, CT 06460-0104
PO BOX 105, MILFORD, CT 06460-0105
PO BOX 106, MILFORD, CT 06460-0106
PO BOX 107, MILFORD, CT 06460-0107
PO BOX 108, MILFORD, CT 06460-0108
PO BOX 109, MILFORD, CT 06460-0109
PO BOX 110, MILFORD, CT 06460-0110
PO BOX 111, MILFORD, CT 06460-0111
PO BOX 112, MILFORD, CT 06460-0112
PO BOX 113, MILFORD, CT 06460-0113
PO BOX 114, MILFORD, CT 06460-0114
PO BOX 115, MILFORD, CT 06460-0115
PO BOX 116, MILFORD, CT 06460-0116
PO BOX 117, MILFORD, CT 06460-0117
PO BOX 118, MILFORD, CT 06460-0118
PO BOX 119, MILFORD, CT 06460-0119
PO BOX 120, MILFORD, CT 06460-0120
PO BOX 121, MILFORD, CT 06460-0121
PO BOX 122, MILFORD, CT 06460-0122
PO BOX 123, MILFORD, CT 06460-0123
PO BOX 124, MILFORD, CT 06460-0124
PO BOX 125, MILFORD, CT 06460-0125
PO BOX 126, MILFORD, CT 06460-0126
PO BOX 127, MILFORD, CT 06460-0127
PO BOX 128, MILFORD, CT 06460-0128
PO BOX 129, MILFORD, CT 06460-0129
PO BOX 130, MILFORD, CT 06460-0130
PO BOX 131, MILFORD, CT 06460-0131
PO BOX 132, MILFORD, CT 06460-0132
PO BOX 133, MILFORD, CT 06460-0133
PO BOX 134, MILFORD, CT 06460-0134
PO BOX 135, MILFORD, CT 06460-0135
PO BOX 136, MILFORD, CT 06460-0136
PO BOX 137, MILFORD, CT 06460-0137
PO BOX 138, MILFORD, CT 06460-0138
PO BOX 139, MILFORD, CT 06460-0139
PO BOX 140, MILFORD, CT 06460-0140
PO BOX 141, MILFORD, CT 06460-0141
PO BOX 142, MILFORD, CT 06460-0142
PO BOX 143, MILFORD, CT 06460-0143
PO BOX 144, MILFORD, CT 06460-0144
PO BOX 145, MILFORD, CT 06460-0145
PO BOX 146, MILFORD, CT 06460-0146
PO BOX 147, MILFORD, CT 06460-0147
PO BOX 148, MILFORD, CT 06460-0148
PO BOX 149, MILFORD, CT 06460-0149
PO BOX 150, MILFORD, CT 06460-0150
PO BOX 151, MILFORD, CT 06460-0151
PO BOX 152, MILFORD, CT 06460-0152
PO BOX 153, MILFORD, CT 06460-0153
PO BOX 154, MILFORD, CT 06460-0154
PO BOX 155, MILFORD, CT 06460-0155
PO BOX 156, MILFORD, CT 06460-0156
PO BOX 157, MILFORD, CT 06460-0157
PO BOX 158, MILFORD, CT 06460-0158
PO BOX 159, MILFORD, CT 06460-0159
PO BOX 160, MILFORD, CT 06460-0160
PO BOX 161, MILFORD, CT 06460-0161
PO BOX 162, MILFORD, CT 06460-0162
PO BOX 163, MILFORD, CT 06460-0163
PO BOX 164, MILFORD, CT 06460-0164
PO BOX 165, MILFORD, CT 06460-0165
PO BOX 166, MILFORD, CT 06460-0166
PO BOX 167, MILFORD, CT 06460-0167
PO BOX 168, MILFORD, CT 06460-0168
PO BOX 169, MILFORD, CT 06460-0169
PO BOX 170, MILFORD, CT 06460-0170
PO BOX 171, MILFORD, CT 06460-0171
PO BOX 172, MILFORD, CT 06460-0172
PO BOX 173, MILFORD, CT 06460-0173
PO BOX 174, MILFORD, CT 06460-0174
PO BOX 175, MILFORD, CT 06460-0175
PO BOX 176, MILFORD, CT 06460-0176
PO BOX 177, MILFORD, CT 06460-0177
PO BOX 178, MILFORD, CT 06460-0178
PO BOX 179, MILFORD, CT 06460-0179
PO BOX 180, MILFORD, CT 06460-0180
PO BOX 181, MILFORD, CT 06460-0181
PO BOX 182, MILFORD, CT 06460-0182
PO BOX 183, MILFORD, CT 06460-0183
PO BOX 184, MILFORD, CT 06460-0184
PO BOX 185, MILFORD, CT 06460-0185
PO BOX 186, MILFORD, CT 06460-0186
PO BOX 187, MILFORD, CT 06460-0187
PO BOX 188, MILFORD, CT 06460-0188
PO BOX 189, MILFORD, CT 06460-0189
PO BOX 190, MILFORD, CT 06460-0190
PO BOX 191, MILFORD, CT 06460-0191
PO BOX 192, MILFORD, CT 06460-0192
PO BOX 193, MILFORD, CT 06460-0193
PO BOX 194, MILFORD, CT 06460-0194
PO BOX 195, MILFORD, CT 06460-0195
PO BOX 196, MILFORD, CT 06460-0196
PO BOX 197, MILFORD, CT 06460-0197
PO BOX 198, MILFORD, CT 06460-0198
PO BOX 199, MILFORD, CT 06460-0199
PO BOX 200, MILFORD, CT 06460-0200
PO BOX 201, MILFORD, CT 06460-0201
PO BOX 202, MILFORD, CT 06460-0202
PO BOX 203, MILFORD, CT 06460-0203
PO BOX 204, MILFORD, CT 06460-0204
PO BOX 205, MILFORD, CT 06460-0205
PO BOX 206, MILFORD, CT 06460-0206
PO BOX 207, MILFORD, CT 06460-0207
PO BOX 208, MILFORD, CT 06460-0208
PO BOX 209, MILFORD, CT 06460-0209
PO BOX 210, MILFORD, CT 06460-0210
PO BOX 211, MILFORD, CT 06460-0211
PO BOX 212, MILFORD, CT 06460-0212
PO BOX 213, MILFORD, CT 06460-0213
PO BOX 214, MILFORD, CT 06460-0214
PO BOX 215, MILFORD, CT 06460-0215
PO BOX 216, MILFORD, CT 06460-0216
PO BOX 217, MILFORD, CT 06460-0217
PO BOX 218, MILFORD, CT 06460-0218
PO BOX 219, MILFORD, CT 06460-0219
PO BOX 220, MILFORD, CT 06460-0220
PO BOX 221, MILFORD, CT 06460-0221