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 423464, SAN FRANCISCO, CA 94142-3464
PO BOX 423465, SAN FRANCISCO, CA 94142-3465
PO BOX 423466, SAN FRANCISCO, CA 94142-3466
PO BOX 423467, SAN FRANCISCO, CA 94142-3467
PO BOX 423468, SAN FRANCISCO, CA 94142-3468
PO BOX 423469, SAN FRANCISCO, CA 94142-3469
PO BOX 423470, SAN FRANCISCO, CA 94142-3470
PO BOX 423471, SAN FRANCISCO, CA 94142-3471
PO BOX 423472, SAN FRANCISCO, CA 94142-3472
PO BOX 423473, SAN FRANCISCO, CA 94142-3473
PO BOX 423474, SAN FRANCISCO, CA 94142-3474
PO BOX 423475, SAN FRANCISCO, CA 94142-3475
PO BOX 423476, SAN FRANCISCO, CA 94142-3476
PO BOX 423477, SAN FRANCISCO, CA 94142-3477
PO BOX 423478, SAN FRANCISCO, CA 94142-3478
PO BOX 423479, SAN FRANCISCO, CA 94142-3479
PO BOX 423480, SAN FRANCISCO, CA 94142-3480
PO BOX 423481, SAN FRANCISCO, CA 94142-3481
PO BOX 423482, SAN FRANCISCO, CA 94142-3482
PO BOX 423483, SAN FRANCISCO, CA 94142-3483
PO BOX 423484, SAN FRANCISCO, CA 94142-3484
PO BOX 423485, SAN FRANCISCO, CA 94142-3485
PO BOX 423486, SAN FRANCISCO, CA 94142-3486
PO BOX 423487, SAN FRANCISCO, CA 94142-3487
PO BOX 423488, SAN FRANCISCO, CA 94142-3488
PO BOX 423489, SAN FRANCISCO, CA 94142-3489
PO BOX 423490, SAN FRANCISCO, CA 94142-3490
PO BOX 423491, SAN FRANCISCO, CA 94142-3491
PO BOX 423492, SAN FRANCISCO, CA 94142-3492
PO BOX 423493, SAN FRANCISCO, CA 94142-3493
PO BOX 423494, SAN FRANCISCO, CA 94142-3494
PO BOX 423495, SAN FRANCISCO, CA 94142-3495
PO BOX 423496, SAN FRANCISCO, CA 94142-3496
PO BOX 423497, SAN FRANCISCO, CA 94142-3497
PO BOX 423498, SAN FRANCISCO, CA 94142-3498
PO BOX 423499, SAN FRANCISCO, CA 94142-3499
PO BOX 423500, SAN FRANCISCO, CA 94142-3500
PO BOX 423501, SAN FRANCISCO, CA 94142-3501
PO BOX 423502, SAN FRANCISCO, CA 94142-3502
PO BOX 423503, SAN FRANCISCO, CA 94142-3503
PO BOX 423504, SAN FRANCISCO, CA 94142-3504
PO BOX 423505, SAN FRANCISCO, CA 94142-3505
PO BOX 423506, SAN FRANCISCO, CA 94142-3506
PO BOX 423507, SAN FRANCISCO, CA 94142-3507
PO BOX 423508, SAN FRANCISCO, CA 94142-3508
PO BOX 423509, SAN FRANCISCO, CA 94142-3509
PO BOX 423510, SAN FRANCISCO, CA 94142-3510
PO BOX 423511, SAN FRANCISCO, CA 94142-3511
PO BOX 423512, SAN FRANCISCO, CA 94142-3512
PO BOX 423513, SAN FRANCISCO, CA 94142-3513
PO BOX 423514, SAN FRANCISCO, CA 94142-3514
PO BOX 423515, SAN FRANCISCO, CA 94142-3515
PO BOX 423516, SAN FRANCISCO, CA 94142-3516
PO BOX 423517, SAN FRANCISCO, CA 94142-3517
PO BOX 423518, SAN FRANCISCO, CA 94142-3518
PO BOX 423519, SAN FRANCISCO, CA 94142-3519
PO BOX 423520, SAN FRANCISCO, CA 94142-3520
PO BOX 423521, SAN FRANCISCO, CA 94142-3521
PO BOX 423522, SAN FRANCISCO, CA 94142-3522
PO BOX 423523, SAN FRANCISCO, CA 94142-3523
PO BOX 423524, SAN FRANCISCO, CA 94142-3524
PO BOX 423525, SAN FRANCISCO, CA 94142-3525
PO BOX 423526, SAN FRANCISCO, CA 94142-3526
PO BOX 423527, SAN FRANCISCO, CA 94142-3527
PO BOX 423528, SAN FRANCISCO, CA 94142-3528
PO BOX 423529, SAN FRANCISCO, CA 94142-3529
PO BOX 423530, SAN FRANCISCO, CA 94142-3530
PO BOX 423531, SAN FRANCISCO, CA 94142-3531
PO BOX 423532, SAN FRANCISCO, CA 94142-3532
PO BOX 423533, SAN FRANCISCO, CA 94142-3533
PO BOX 423534, SAN FRANCISCO, CA 94142-3534
PO BOX 423535, SAN FRANCISCO, CA 94142-3535
PO BOX 423536, SAN FRANCISCO, CA 94142-3536
PO BOX 423537, SAN FRANCISCO, CA 94142-3537
PO BOX 423538, SAN FRANCISCO, CA 94142-3538
PO BOX 423539, SAN FRANCISCO, CA 94142-3539
PO BOX 423540, SAN FRANCISCO, CA 94142-3540
PO BOX 423541, SAN FRANCISCO, CA 94142-3541
PO BOX 423542, SAN FRANCISCO, CA 94142-3542
PO BOX 423543, SAN FRANCISCO, CA 94142-3543
PO BOX 423544, SAN FRANCISCO, CA 94142-3544
PO BOX 423545, SAN FRANCISCO, CA 94142-3545
PO BOX 423546, SAN FRANCISCO, CA 94142-3546
PO BOX 423547, SAN FRANCISCO, CA 94142-3547
PO BOX 423548, SAN FRANCISCO, CA 94142-3548
PO BOX 423549, SAN FRANCISCO, CA 94142-3549
PO BOX 423550, SAN FRANCISCO, CA 94142-3550
PO BOX 423551, SAN FRANCISCO, CA 94142-3551
PO BOX 423552, SAN FRANCISCO, CA 94142-3552
PO BOX 423553, SAN FRANCISCO, CA 94142-3553
PO BOX 423554, SAN FRANCISCO, CA 94142-3554
PO BOX 423555, SAN FRANCISCO, CA 94142-3555
PO BOX 423556, SAN FRANCISCO, CA 94142-3556
PO BOX 423557, SAN FRANCISCO, CA 94142-3557
PO BOX 423558, SAN FRANCISCO, CA 94142-3558
PO BOX 423559, SAN FRANCISCO, CA 94142-3559
PO BOX 423560, SAN FRANCISCO, CA 94142-3560
PO BOX 423561, SAN FRANCISCO, CA 94142-3561
PO BOX 423562, SAN FRANCISCO, CA 94142-3562
PO BOX 423563, SAN FRANCISCO, CA 94142-3563
PO BOX 423564, SAN FRANCISCO, CA 94142-3564
PO BOX 423565, SAN FRANCISCO, CA 94142-3565
PO BOX 423566, SAN FRANCISCO, CA 94142-3566
PO BOX 423567, SAN FRANCISCO, CA 94142-3567
PO BOX 423568, SAN FRANCISCO, CA 94142-3568
PO BOX 423569, SAN FRANCISCO, CA 94142-3569
PO BOX 423570, SAN FRANCISCO, CA 94142-3570
PO BOX 423571, SAN FRANCISCO, CA 94142-3571
PO BOX 423572, SAN FRANCISCO, CA 94142-3572
PO BOX 423573, SAN FRANCISCO, CA 94142-3573
PO BOX 423574, SAN FRANCISCO, CA 94142-3574
PO BOX 423575, SAN FRANCISCO, CA 94142-3575
PO BOX 423576, SAN FRANCISCO, CA 94142-3576
PO BOX 423577, SAN FRANCISCO, CA 94142-3577
PO BOX 423578, SAN FRANCISCO, CA 94142-3578
PO BOX 423579, SAN FRANCISCO, CA 94142-3579
PO BOX 423580, SAN FRANCISCO, CA 94142-3580
PO BOX 423581, SAN FRANCISCO, CA 94142-3581
PO BOX 423582, SAN FRANCISCO, CA 94142-3582
PO BOX 423583, SAN FRANCISCO, CA 94142-3583
PO BOX 423584, SAN FRANCISCO, CA 94142-3584
PO BOX 423585, SAN FRANCISCO, CA 94142-3585
PO BOX 423586, SAN FRANCISCO, CA 94142-3586
PO BOX 423587, SAN FRANCISCO, CA 94142-3587
PO BOX 423588, SAN FRANCISCO, CA 94142-3588
PO BOX 423589, SAN FRANCISCO, CA 94142-3589
PO BOX 423590, SAN FRANCISCO, CA 94142-3590
PO BOX 423591, SAN FRANCISCO, CA 94142-3591
PO BOX 423592, SAN FRANCISCO, CA 94142-3592
PO BOX 423593, SAN FRANCISCO, CA 94142-3593
PO BOX 423594, SAN FRANCISCO, CA 94142-3594
PO BOX 423595, SAN FRANCISCO, CA 94142-3595
PO BOX 423596, SAN FRANCISCO, CA 94142-3596
PO BOX 423597, SAN FRANCISCO, CA 94142-3597
PO BOX 423598, SAN FRANCISCO, CA 94142-3598
PO BOX 423599, SAN FRANCISCO, CA 94142-3599
PO BOX 423600, SAN FRANCISCO, CA 94142-3600
PO BOX 423601, SAN FRANCISCO, CA 94142-3601
PO BOX 423602, SAN FRANCISCO, CA 94142-3602
PO BOX 423603, SAN FRANCISCO, CA 94142-3603
PO BOX 423604, SAN FRANCISCO, CA 94142-3604
PO BOX 423605, SAN FRANCISCO, CA 94142-3605
PO BOX 423606, SAN FRANCISCO, CA 94142-3606
PO BOX 423607, SAN FRANCISCO, CA 94142-3607
PO BOX 423608, SAN FRANCISCO, CA 94142-3608
PO BOX 423609, SAN FRANCISCO, CA 94142-3609
PO BOX 423610, SAN FRANCISCO, CA 94142-3610
PO BOX 423611, SAN FRANCISCO, CA 94142-3611
PO BOX 423612, SAN FRANCISCO, CA 94142-3612
PO BOX 423613, SAN FRANCISCO, CA 94142-3613
PO BOX 423614, SAN FRANCISCO, CA 94142-3614
PO BOX 423615, SAN FRANCISCO, CA 94142-3615
PO BOX 423616, SAN FRANCISCO, CA 94142-3616
PO BOX 423617, SAN FRANCISCO, CA 94142-3617
PO BOX 423618, SAN FRANCISCO, CA 94142-3618
PO BOX 423619, SAN FRANCISCO, CA 94142-3619
PO BOX 423620, SAN FRANCISCO, CA 94142-3620
PO BOX 423621, SAN FRANCISCO, CA 94142-3621
PO BOX 423622, SAN FRANCISCO, CA 94142-3622
PO BOX 423623, SAN FRANCISCO, CA 94142-3623
PO BOX 423624, SAN FRANCISCO, CA 94142-3624
PO BOX 423625, SAN FRANCISCO, CA 94142-3625
PO BOX 423626, SAN FRANCISCO, CA 94142-3626
PO BOX 423627, SAN FRANCISCO, CA 94142-3627
PO BOX 423628, SAN FRANCISCO, CA 94142-3628
PO BOX 423629, SAN FRANCISCO, CA 94142-3629
PO BOX 423630, SAN FRANCISCO, CA 94142-3630
PO BOX 423631, SAN FRANCISCO, CA 94142-3631
PO BOX 423632, SAN FRANCISCO, CA 94142-3632
PO BOX 423633, SAN FRANCISCO, CA 94142-3633
PO BOX 423634, SAN FRANCISCO, CA 94142-3634
PO BOX 423635, SAN FRANCISCO, CA 94142-3635
PO BOX 423636, SAN FRANCISCO, CA 94142-3636
PO BOX 423637, SAN FRANCISCO, CA 94142-3637
PO BOX 423638, SAN FRANCISCO, CA 94142-3638
PO BOX 423639, SAN FRANCISCO, CA 94142-3639
PO BOX 423640, SAN FRANCISCO, CA 94142-3640
PO BOX 423641, SAN FRANCISCO, CA 94142-3641
PO BOX 423642, SAN FRANCISCO, CA 94142-3642
PO BOX 423643, SAN FRANCISCO, CA 94142-3643
PO BOX 423644, SAN FRANCISCO, CA 94142-3644
PO BOX 423645, SAN FRANCISCO, CA 94142-3645
PO BOX 423646, SAN FRANCISCO, CA 94142-3646
PO BOX 423647, SAN FRANCISCO, CA 94142-3647
PO BOX 423648, SAN FRANCISCO, CA 94142-3648
PO BOX 423649, SAN FRANCISCO, CA 94142-3649
PO BOX 423650, SAN FRANCISCO, CA 94142-3650
PO BOX 423651, SAN FRANCISCO, CA 94142-3651
PO BOX 423652, SAN FRANCISCO, CA 94142-3652
PO BOX 423653, SAN FRANCISCO, CA 94142-3653
PO BOX 423654, SAN FRANCISCO, CA 94142-3654
PO BOX 423655, SAN FRANCISCO, CA 94142-3655
PO BOX 423656, SAN FRANCISCO, CA 94142-3656
PO BOX 423657, SAN FRANCISCO, CA 94142-3657
PO BOX 423658, SAN FRANCISCO, CA 94142-3658
PO BOX 423659, SAN FRANCISCO, CA 94142-3659
PO BOX 423660, SAN FRANCISCO, CA 94142-3660
PO BOX 423661, SAN FRANCISCO, CA 94142-3661
PO BOX 423662, SAN FRANCISCO, CA 94142-3662