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 33371, RIVERSIDE, CA 92519-0371
PO BOX 33372, RIVERSIDE, CA 92519-0372
PO BOX 33373, RIVERSIDE, CA 92519-0373
PO BOX 33374, RIVERSIDE, CA 92519-0374
PO BOX 33375, RIVERSIDE, CA 92519-0375
PO BOX 33376, RIVERSIDE, CA 92519-0376
PO BOX 33377, RIVERSIDE, CA 92519-0377
PO BOX 33378, RIVERSIDE, CA 92519-0378
PO BOX 33379, RIVERSIDE, CA 92519-0379
PO BOX 33380, RIVERSIDE, CA 92519-0380
PO BOX 33381, RIVERSIDE, CA 92519-0381
PO BOX 33382, RIVERSIDE, CA 92519-0382
PO BOX 33383, RIVERSIDE, CA 92519-0383
PO BOX 33384, RIVERSIDE, CA 92519-0384
PO BOX 33385, RIVERSIDE, CA 92519-0385
PO BOX 33386, RIVERSIDE, CA 92519-0386
PO BOX 33387, RIVERSIDE, CA 92519-0387
PO BOX 33388, RIVERSIDE, CA 92519-0388
PO BOX 33389, RIVERSIDE, CA 92519-0389
PO BOX 33390, RIVERSIDE, CA 92519-0390
PO BOX 33391, RIVERSIDE, CA 92519-0391
PO BOX 33392, RIVERSIDE, CA 92519-0392
PO BOX 33393, RIVERSIDE, CA 92519-0393
PO BOX 33394, RIVERSIDE, CA 92519-0394
PO BOX 33395, RIVERSIDE, CA 92519-0395
PO BOX 33396, RIVERSIDE, CA 92519-0396
PO BOX 33397, RIVERSIDE, CA 92519-0397
PO BOX 33398, RIVERSIDE, CA 92519-0398
PO BOX 33399, RIVERSIDE, CA 92519-0399
PO BOX 33400, RIVERSIDE, CA 92519-0400
PO BOX 33401, RIVERSIDE, CA 92519-0401
PO BOX 33402, RIVERSIDE, CA 92519-0402
PO BOX 33403, RIVERSIDE, CA 92519-0403
PO BOX 33404, RIVERSIDE, CA 92519-0404
PO BOX 33405, RIVERSIDE, CA 92519-0405
PO BOX 33406, RIVERSIDE, CA 92519-0406
PO BOX 33407, RIVERSIDE, CA 92519-0407
PO BOX 33408, RIVERSIDE, CA 92519-0408
PO BOX 33409, RIVERSIDE, CA 92519-0409
PO BOX 33410, RIVERSIDE, CA 92519-0410
PO BOX 33411, RIVERSIDE, CA 92519-0411
PO BOX 33412, RIVERSIDE, CA 92519-0412
PO BOX 33413, RIVERSIDE, CA 92519-0413
PO BOX 33414, RIVERSIDE, CA 92519-0414
PO BOX 33415, RIVERSIDE, CA 92519-0415
PO BOX 33416, RIVERSIDE, CA 92519-0416
PO BOX 33417, RIVERSIDE, CA 92519-0417
PO BOX 33418, RIVERSIDE, CA 92519-0418
PO BOX 33419, RIVERSIDE, CA 92519-0419
PO BOX 33420, RIVERSIDE, CA 92519-0420
PO BOX 33421, RIVERSIDE, CA 92519-0421
PO BOX 33422, RIVERSIDE, CA 92519-0422
PO BOX 33423, RIVERSIDE, CA 92519-0423
PO BOX 33424, RIVERSIDE, CA 92519-0424
PO BOX 33425, RIVERSIDE, CA 92519-0425
PO BOX 33426, RIVERSIDE, CA 92519-0426
PO BOX 33427, RIVERSIDE, CA 92519-0427
PO BOX 33428, RIVERSIDE, CA 92519-0428
PO BOX 33429, RIVERSIDE, CA 92519-0429
PO BOX 33430, RIVERSIDE, CA 92519-0430
PO BOX 33431, RIVERSIDE, CA 92519-0431
PO BOX 33432, RIVERSIDE, CA 92519-0432
PO BOX 33433, RIVERSIDE, CA 92519-0433
PO BOX 33434, RIVERSIDE, CA 92519-0434
PO BOX 33435, RIVERSIDE, CA 92519-0435
PO BOX 33436, RIVERSIDE, CA 92519-0436
PO BOX 33437, RIVERSIDE, CA 92519-0437
PO BOX 33438, RIVERSIDE, CA 92519-0438
PO BOX 33439, RIVERSIDE, CA 92519-0439
PO BOX 33440, RIVERSIDE, CA 92519-0440
PO BOX 33441, RIVERSIDE, CA 92519-0441
PO BOX 33442, RIVERSIDE, CA 92519-0442
PO BOX 33443, RIVERSIDE, CA 92519-0443
PO BOX 33444, RIVERSIDE, CA 92519-0444
PO BOX 33445, RIVERSIDE, CA 92519-0445
PO BOX 33446, RIVERSIDE, CA 92519-0446
PO BOX 33447, RIVERSIDE, CA 92519-0447
PO BOX 33448, RIVERSIDE, CA 92519-0448
PO BOX 33449, RIVERSIDE, CA 92519-0449
PO BOX 33450, RIVERSIDE, CA 92519-0450
PO BOX 33451, RIVERSIDE, CA 92519-0451
PO BOX 33452, RIVERSIDE, CA 92519-0452
PO BOX 33453, RIVERSIDE, CA 92519-0453
PO BOX 33454, RIVERSIDE, CA 92519-0454
PO BOX 33455, RIVERSIDE, CA 92519-0455
PO BOX 33456, RIVERSIDE, CA 92519-0456
PO BOX 33457, RIVERSIDE, CA 92519-0457
PO BOX 33458, RIVERSIDE, CA 92519-0458
PO BOX 33459, RIVERSIDE, CA 92519-0459
PO BOX 33460, RIVERSIDE, CA 92519-0460
PO BOX 33461, RIVERSIDE, CA 92519-0461
PO BOX 33462, RIVERSIDE, CA 92519-0462
PO BOX 33463, RIVERSIDE, CA 92519-0463
PO BOX 33464, RIVERSIDE, CA 92519-0464
PO BOX 33465, RIVERSIDE, CA 92519-0465
PO BOX 33466, RIVERSIDE, CA 92519-0466
PO BOX 33467, RIVERSIDE, CA 92519-0467
PO BOX 33468, RIVERSIDE, CA 92519-0468
PO BOX 33469, RIVERSIDE, CA 92519-0469
PO BOX 33470, RIVERSIDE, CA 92519-0470
PO BOX 33471, RIVERSIDE, CA 92519-0471
PO BOX 33472, RIVERSIDE, CA 92519-0472
PO BOX 33473, RIVERSIDE, CA 92519-0473
PO BOX 33474, RIVERSIDE, CA 92519-0474
PO BOX 33475, RIVERSIDE, CA 92519-0475
PO BOX 33476, RIVERSIDE, CA 92519-0476
PO BOX 33477, RIVERSIDE, CA 92519-0477
PO BOX 33478, RIVERSIDE, CA 92519-0478
PO BOX 33479, RIVERSIDE, CA 92519-0479
PO BOX 33480, RIVERSIDE, CA 92519-0480
PO BOX 33481, RIVERSIDE, CA 92519-0481
PO BOX 33482, RIVERSIDE, CA 92519-0482
PO BOX 33483, RIVERSIDE, CA 92519-0483
PO BOX 33484, RIVERSIDE, CA 92519-0484
PO BOX 33485, RIVERSIDE, CA 92519-0485
PO BOX 33486, RIVERSIDE, CA 92519-0486
PO BOX 33487, RIVERSIDE, CA 92519-0487
PO BOX 33488, RIVERSIDE, CA 92519-0488
PO BOX 33489, RIVERSIDE, CA 92519-0489
PO BOX 33490, RIVERSIDE, CA 92519-0490
PO BOX 33491, RIVERSIDE, CA 92519-0491
PO BOX 33492, RIVERSIDE, CA 92519-0492
PO BOX 33493, RIVERSIDE, CA 92519-0493
PO BOX 33494, RIVERSIDE, CA 92519-0494
PO BOX 33495, RIVERSIDE, CA 92519-0495
PO BOX 33496, RIVERSIDE, CA 92519-0496
PO BOX 33497, RIVERSIDE, CA 92519-0497
PO BOX 33498, RIVERSIDE, CA 92519-0498
PO BOX 33499, RIVERSIDE, CA 92519-0499
PO BOX 33500, RIVERSIDE, CA 92519-0500
PO BOX 33501, RIVERSIDE, CA 92519-0501
PO BOX 33502, RIVERSIDE, CA 92519-0502
PO BOX 33503, RIVERSIDE, CA 92519-0503
PO BOX 33504, RIVERSIDE, CA 92519-0504
PO BOX 33505, RIVERSIDE, CA 92519-0505
PO BOX 33506, RIVERSIDE, CA 92519-0506
PO BOX 33507, RIVERSIDE, CA 92519-0507
PO BOX 33508, RIVERSIDE, CA 92519-0508
PO BOX 33509, RIVERSIDE, CA 92519-0509
PO BOX 33510, RIVERSIDE, CA 92519-0510
PO BOX 33511, RIVERSIDE, CA 92519-0511
PO BOX 33512, RIVERSIDE, CA 92519-0512
PO BOX 33513, RIVERSIDE, CA 92519-0513
PO BOX 33514, RIVERSIDE, CA 92519-0514
PO BOX 33515, RIVERSIDE, CA 92519-0515
PO BOX 33516, RIVERSIDE, CA 92519-0516
PO BOX 33517, RIVERSIDE, CA 92519-0517
PO BOX 33518, RIVERSIDE, CA 92519-0518
PO BOX 33519, RIVERSIDE, CA 92519-0519
PO BOX 33520, RIVERSIDE, CA 92519-0520
PO BOX 33521, RIVERSIDE, CA 92519-0521
PO BOX 33522, RIVERSIDE, CA 92519-0522
PO BOX 33523, RIVERSIDE, CA 92519-0523
PO BOX 33524, RIVERSIDE, CA 92519-0524
PO BOX 33525, RIVERSIDE, CA 92519-0525
PO BOX 33526, RIVERSIDE, CA 92519-0526
PO BOX 33527, RIVERSIDE, CA 92519-0527
PO BOX 33528, RIVERSIDE, CA 92519-0528
PO BOX 33529, RIVERSIDE, CA 92519-0529
PO BOX 33530, RIVERSIDE, CA 92519-0530
PO BOX 33531, RIVERSIDE, CA 92519-0531
PO BOX 33532, RIVERSIDE, CA 92519-0532
PO BOX 33533, RIVERSIDE, CA 92519-0533
PO BOX 33534, RIVERSIDE, CA 92519-0534
PO BOX 33535, RIVERSIDE, CA 92519-0535
PO BOX 33536, RIVERSIDE, CA 92519-0536
PO BOX 33537, RIVERSIDE, CA 92519-0537
PO BOX 33538, RIVERSIDE, CA 92519-0538
PO BOX 33539, RIVERSIDE, CA 92519-0539
PO BOX 33540, RIVERSIDE, CA 92519-0540
PO BOX 33541, RIVERSIDE, CA 92519-0541
PO BOX 33542, RIVERSIDE, CA 92519-0542
PO BOX 33543, RIVERSIDE, CA 92519-0543
PO BOX 33544, RIVERSIDE, CA 92519-0544
PO BOX 33545, RIVERSIDE, CA 92519-0545
PO BOX 33546, RIVERSIDE, CA 92519-0546
PO BOX 33547, RIVERSIDE, CA 92519-0547
PO BOX 33548, RIVERSIDE, CA 92519-0548
PO BOX 33549, RIVERSIDE, CA 92519-0549
PO BOX 33550, RIVERSIDE, CA 92519-0550
PO BOX 33551, RIVERSIDE, CA 92519-0551
PO BOX 33552, RIVERSIDE, CA 92519-0552
PO BOX 33553, RIVERSIDE, CA 92519-0553
PO BOX 33554, RIVERSIDE, CA 92519-0554
PO BOX 33555, RIVERSIDE, CA 92519-0555