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 10, SOUTH BELOIT, IL 61080-0010
PO BOX 11, SOUTH BELOIT, IL 61080-0011
PO BOX 12, SOUTH BELOIT, IL 61080-0012
PO BOX 13, SOUTH BELOIT, IL 61080-0013
PO BOX 14, SOUTH BELOIT, IL 61080-0014
PO BOX 15, SOUTH BELOIT, IL 61080-0015
PO BOX 16, SOUTH BELOIT, IL 61080-0016
PO BOX 17, SOUTH BELOIT, IL 61080-0017
PO BOX 18, SOUTH BELOIT, IL 61080-0018
PO BOX 19, SOUTH BELOIT, IL 61080-0019
PO BOX 20, SOUTH BELOIT, IL 61080-0020
PO BOX 21, SOUTH BELOIT, IL 61080-0021
PO BOX 22, SOUTH BELOIT, IL 61080-0022
PO BOX 23, SOUTH BELOIT, IL 61080-0023
PO BOX 24, SOUTH BELOIT, IL 61080-0024
PO BOX 25, SOUTH BELOIT, IL 61080-0025
PO BOX 26, SOUTH BELOIT, IL 61080-0026
PO BOX 27, SOUTH BELOIT, IL 61080-0027
PO BOX 28, SOUTH BELOIT, IL 61080-0028
PO BOX 29, SOUTH BELOIT, IL 61080-0029
PO BOX 30, SOUTH BELOIT, IL 61080-0030
PO BOX 31, SOUTH BELOIT, IL 61080-0031
PO BOX 32, SOUTH BELOIT, IL 61080-0032
PO BOX 33, SOUTH BELOIT, IL 61080-0033
PO BOX 34, SOUTH BELOIT, IL 61080-0034
PO BOX 35, SOUTH BELOIT, IL 61080-0035
PO BOX 36, SOUTH BELOIT, IL 61080-0036
PO BOX 37, SOUTH BELOIT, IL 61080-0037
PO BOX 38, SOUTH BELOIT, IL 61080-0038
PO BOX 39, SOUTH BELOIT, IL 61080-0039
PO BOX 40, SOUTH BELOIT, IL 61080-0040
PO BOX 41, SOUTH BELOIT, IL 61080-0041
PO BOX 42, SOUTH BELOIT, IL 61080-0042
PO BOX 43, SOUTH BELOIT, IL 61080-0043
PO BOX 44, SOUTH BELOIT, IL 61080-0044
PO BOX 45, SOUTH BELOIT, IL 61080-0045
PO BOX 46, SOUTH BELOIT, IL 61080-0046
PO BOX 47, SOUTH BELOIT, IL 61080-0047
PO BOX 48, SOUTH BELOIT, IL 61080-0048
PO BOX 49, SOUTH BELOIT, IL 61080-0049
PO BOX 50, SOUTH BELOIT, IL 61080-0050
PO BOX 51, SOUTH BELOIT, IL 61080-0051
PO BOX 52, SOUTH BELOIT, IL 61080-0052
PO BOX 53, SOUTH BELOIT, IL 61080-0053
PO BOX 54, SOUTH BELOIT, IL 61080-0054
PO BOX 55, SOUTH BELOIT, IL 61080-0055
PO BOX 56, SOUTH BELOIT, IL 61080-0056
PO BOX 57, SOUTH BELOIT, IL 61080-0057
PO BOX 58, SOUTH BELOIT, IL 61080-0058
PO BOX 59, SOUTH BELOIT, IL 61080-0059
PO BOX 60, SOUTH BELOIT, IL 61080-0060
PO BOX 61, SOUTH BELOIT, IL 61080-0061
PO BOX 62, SOUTH BELOIT, IL 61080-0062
PO BOX 63, SOUTH BELOIT, IL 61080-0063
PO BOX 64, SOUTH BELOIT, IL 61080-0064
PO BOX 65, SOUTH BELOIT, IL 61080-0065
PO BOX 66, SOUTH BELOIT, IL 61080-0066
PO BOX 67, SOUTH BELOIT, IL 61080-0067
PO BOX 68, SOUTH BELOIT, IL 61080-0068
PO BOX 69, SOUTH BELOIT, IL 61080-0069
PO BOX 70, SOUTH BELOIT, IL 61080-0070
PO BOX 71, SOUTH BELOIT, IL 61080-0071
PO BOX 72, SOUTH BELOIT, IL 61080-0072
PO BOX 73, SOUTH BELOIT, IL 61080-0073
PO BOX 74, SOUTH BELOIT, IL 61080-0074
PO BOX 75, SOUTH BELOIT, IL 61080-0075
PO BOX 76, SOUTH BELOIT, IL 61080-0076
PO BOX 77, SOUTH BELOIT, IL 61080-0077
PO BOX 78, SOUTH BELOIT, IL 61080-0078
PO BOX 79, SOUTH BELOIT, IL 61080-0079
PO BOX 80, SOUTH BELOIT, IL 61080-0080
PO BOX 81, SOUTH BELOIT, IL 61080-0081
PO BOX 82, SOUTH BELOIT, IL 61080-0082
PO BOX 83, SOUTH BELOIT, IL 61080-0083
PO BOX 84, SOUTH BELOIT, IL 61080-0084
PO BOX 85, SOUTH BELOIT, IL 61080-0085
PO BOX 86, SOUTH BELOIT, IL 61080-0086
PO BOX 87, SOUTH BELOIT, IL 61080-0087
PO BOX 88, SOUTH BELOIT, IL 61080-0088
PO BOX 89, SOUTH BELOIT, IL 61080-0089
PO BOX 90, SOUTH BELOIT, IL 61080-0090
PO BOX 91, SOUTH BELOIT, IL 61080-0091
PO BOX 92, SOUTH BELOIT, IL 61080-0092
PO BOX 93, SOUTH BELOIT, IL 61080-0093
PO BOX 94, SOUTH BELOIT, IL 61080-0094
PO BOX 95, SOUTH BELOIT, IL 61080-0095
PO BOX 96, SOUTH BELOIT, IL 61080-0096
PO BOX 97, SOUTH BELOIT, IL 61080-0097
PO BOX 98, SOUTH BELOIT, IL 61080-0098
PO BOX 99, SOUTH BELOIT, IL 61080-0099
PO BOX 100, SOUTH BELOIT, IL 61080-0100
PO BOX 101, SOUTH BELOIT, IL 61080-0101
PO BOX 102, SOUTH BELOIT, IL 61080-0102
PO BOX 103, SOUTH BELOIT, IL 61080-0103
PO BOX 104, SOUTH BELOIT, IL 61080-0104
PO BOX 105, SOUTH BELOIT, IL 61080-0105
PO BOX 106, SOUTH BELOIT, IL 61080-0106
PO BOX 107, SOUTH BELOIT, IL 61080-0107
PO BOX 108, SOUTH BELOIT, IL 61080-0108
PO BOX 109, SOUTH BELOIT, IL 61080-0109
PO BOX 110, SOUTH BELOIT, IL 61080-0110
PO BOX 111, SOUTH BELOIT, IL 61080-0111
PO BOX 112, SOUTH BELOIT, IL 61080-0112
PO BOX 113, SOUTH BELOIT, IL 61080-0113
PO BOX 114, SOUTH BELOIT, IL 61080-0114
PO BOX 115, SOUTH BELOIT, IL 61080-0115
PO BOX 116, SOUTH BELOIT, IL 61080-0116
PO BOX 117, SOUTH BELOIT, IL 61080-0117
PO BOX 118, SOUTH BELOIT, IL 61080-0118
PO BOX 119, SOUTH BELOIT, IL 61080-0119
PO BOX 120, SOUTH BELOIT, IL 61080-0120
PO BOX 121, SOUTH BELOIT, IL 61080-0121
PO BOX 122, SOUTH BELOIT, IL 61080-0122
PO BOX 123, SOUTH BELOIT, IL 61080-0123
PO BOX 124, SOUTH BELOIT, IL 61080-0124
PO BOX 125, SOUTH BELOIT, IL 61080-0125
PO BOX 126, SOUTH BELOIT, IL 61080-0126
PO BOX 127, SOUTH BELOIT, IL 61080-0127
PO BOX 128, SOUTH BELOIT, IL 61080-0128
PO BOX 129, SOUTH BELOIT, IL 61080-0129
PO BOX 130, SOUTH BELOIT, IL 61080-0130
PO BOX 131, SOUTH BELOIT, IL 61080-0131
PO BOX 132, SOUTH BELOIT, IL 61080-0132
PO BOX 133, SOUTH BELOIT, IL 61080-0133
PO BOX 134, SOUTH BELOIT, IL 61080-0134
PO BOX 135, SOUTH BELOIT, IL 61080-0135
PO BOX 136, SOUTH BELOIT, IL 61080-0136
PO BOX 137, SOUTH BELOIT, IL 61080-0137
PO BOX 138, SOUTH BELOIT, IL 61080-0138
PO BOX 139, SOUTH BELOIT, IL 61080-0139
PO BOX 140, SOUTH BELOIT, IL 61080-0140
PO BOX 141, SOUTH BELOIT, IL 61080-0141
PO BOX 142, SOUTH BELOIT, IL 61080-0142
PO BOX 143, SOUTH BELOIT, IL 61080-0143
PO BOX 144, SOUTH BELOIT, IL 61080-0144
PO BOX 145, SOUTH BELOIT, IL 61080-0145
PO BOX 146, SOUTH BELOIT, IL 61080-0146
PO BOX 147, SOUTH BELOIT, IL 61080-0147
PO BOX 148, SOUTH BELOIT, IL 61080-0148
PO BOX 149, SOUTH BELOIT, IL 61080-0149
PO BOX 150, SOUTH BELOIT, IL 61080-0150
PO BOX 151, SOUTH BELOIT, IL 61080-0151
PO BOX 152, SOUTH BELOIT, IL 61080-0152
PO BOX 153, SOUTH BELOIT, IL 61080-0153
PO BOX 154, SOUTH BELOIT, IL 61080-0154
PO BOX 155, SOUTH BELOIT, IL 61080-0155
PO BOX 156, SOUTH BELOIT, IL 61080-0156
PO BOX 157, SOUTH BELOIT, IL 61080-0157
PO BOX 158, SOUTH BELOIT, IL 61080-0158
PO BOX 159, SOUTH BELOIT, IL 61080-0159
PO BOX 160, SOUTH BELOIT, IL 61080-0160
PO BOX 161, SOUTH BELOIT, IL 61080-0161
PO BOX 162, SOUTH BELOIT, IL 61080-0162
PO BOX 163, SOUTH BELOIT, IL 61080-0163
PO BOX 164, SOUTH BELOIT, IL 61080-0164
PO BOX 165, SOUTH BELOIT, IL 61080-0165
PO BOX 166, SOUTH BELOIT, IL 61080-0166
PO BOX 167, SOUTH BELOIT, IL 61080-0167
PO BOX 168, SOUTH BELOIT, IL 61080-0168
PO BOX 169, SOUTH BELOIT, IL 61080-0169
PO BOX 170, SOUTH BELOIT, IL 61080-0170
PO BOX 171, SOUTH BELOIT, IL 61080-0171
PO BOX 172, SOUTH BELOIT, IL 61080-0172
PO BOX 173, SOUTH BELOIT, IL 61080-0173
PO BOX 174, SOUTH BELOIT, IL 61080-0174
PO BOX 175, SOUTH BELOIT, IL 61080-0175
PO BOX 176, SOUTH BELOIT, IL 61080-0176
PO BOX 177, SOUTH BELOIT, IL 61080-0177
PO BOX 178, SOUTH BELOIT, IL 61080-0178
PO BOX 179, SOUTH BELOIT, IL 61080-0179
PO BOX 180, SOUTH BELOIT, IL 61080-0180
PO BOX 181, SOUTH BELOIT, IL 61080-0181
PO BOX 182, SOUTH BELOIT, IL 61080-0182
PO BOX 183, SOUTH BELOIT, IL 61080-0183
PO BOX 184, SOUTH BELOIT, IL 61080-0184
PO BOX 185, SOUTH BELOIT, IL 61080-0185
PO BOX 186, SOUTH BELOIT, IL 61080-0186
PO BOX 187, SOUTH BELOIT, IL 61080-0187
PO BOX 188, SOUTH BELOIT, IL 61080-0188
PO BOX 189, SOUTH BELOIT, IL 61080-0189
PO BOX 190, SOUTH BELOIT, IL 61080-0190
PO BOX 191, SOUTH BELOIT, IL 61080-0191
PO BOX 192, SOUTH BELOIT, IL 61080-0192
PO BOX 193, SOUTH BELOIT, IL 61080-0193
PO BOX 194, SOUTH BELOIT, IL 61080-0194
PO BOX 195, SOUTH BELOIT, IL 61080-0195
PO BOX 196, SOUTH BELOIT, IL 61080-0196
PO BOX 197, SOUTH BELOIT, IL 61080-0197
PO BOX 198, SOUTH BELOIT, IL 61080-0198
PO BOX 199, SOUTH BELOIT, IL 61080-0199
PO BOX 200, SOUTH BELOIT, IL 61080-0200
PO BOX 201, SOUTH BELOIT, IL 61080-0201
PO BOX 202, SOUTH BELOIT, IL 61080-0202
PO BOX 203, SOUTH BELOIT, IL 61080-0203
PO BOX 204, SOUTH BELOIT, IL 61080-0204
PO BOX 205, SOUTH BELOIT, IL 61080-0205
PO BOX 206, SOUTH BELOIT, IL 61080-0206
PO BOX 207, SOUTH BELOIT, IL 61080-0207
PO BOX 208, SOUTH BELOIT, IL 61080-0208
PO BOX 209, SOUTH BELOIT, IL 61080-0209
PO BOX 210, SOUTH BELOIT, IL 61080-0210