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 641773, PITTSBURGH, PA 15264-1773
PO BOX 641774, PITTSBURGH, PA 15264-1774
PO BOX 641775, PITTSBURGH, PA 15264-1775
PO BOX 641776, PITTSBURGH, PA 15264-1776
PO BOX 641777, PITTSBURGH, PA 15264-1777
PO BOX 641778, PITTSBURGH, PA 15264-1778
PO BOX 641779, PITTSBURGH, PA 15264-1779
PO BOX 641780, PITTSBURGH, PA 15264-1780
PO BOX 641781, PITTSBURGH, PA 15264-1781
PO BOX 641782, PITTSBURGH, PA 15264-1782
PO BOX 641783, PITTSBURGH, PA 15264-1783
PO BOX 641784, PITTSBURGH, PA 15264-1784
PO BOX 641785, PITTSBURGH, PA 15264-1785
PO BOX 641786, PITTSBURGH, PA 15264-1786
PO BOX 641787, PITTSBURGH, PA 15264-1787
PO BOX 641788, PITTSBURGH, PA 15264-1788
PO BOX 641789, PITTSBURGH, PA 15264-1789
PO BOX 641790, PITTSBURGH, PA 15264-1790
PO BOX 641791, PITTSBURGH, PA 15264-1791
PO BOX 641792, PITTSBURGH, PA 15264-1792
PO BOX 641793, PITTSBURGH, PA 15264-1793
PO BOX 641794, PITTSBURGH, PA 15264-1794
PO BOX 641795, PITTSBURGH, PA 15264-1795
PO BOX 641796, PITTSBURGH, PA 15264-1796
PO BOX 641797, PITTSBURGH, PA 15264-1797
PO BOX 641798, PITTSBURGH, PA 15264-1798
PO BOX 641799, PITTSBURGH, PA 15264-1799
PO BOX 641800, PITTSBURGH, PA 15264-1800
PO BOX 641801, PITTSBURGH, PA 15264-1801
PO BOX 641802, PITTSBURGH, PA 15264-1802
PO BOX 641803, PITTSBURGH, PA 15264-1803
PO BOX 641804, PITTSBURGH, PA 15264-1804
PO BOX 641805, PITTSBURGH, PA 15264-1805
PO BOX 641806, PITTSBURGH, PA 15264-1806
PO BOX 641807, PITTSBURGH, PA 15264-1807
PO BOX 641808, PITTSBURGH, PA 15264-1808
PO BOX 641809, PITTSBURGH, PA 15264-1809
PO BOX 641810, PITTSBURGH, PA 15264-1810
PO BOX 641811, PITTSBURGH, PA 15264-1811
PO BOX 641812, PITTSBURGH, PA 15264-1812
PO BOX 641813, PITTSBURGH, PA 15264-1813
PO BOX 641814, PITTSBURGH, PA 15264-1814
PO BOX 641815, PITTSBURGH, PA 15264-1815
PO BOX 641816, PITTSBURGH, PA 15264-1816
PO BOX 641817, PITTSBURGH, PA 15264-1817
PO BOX 641818, PITTSBURGH, PA 15264-1818
PO BOX 641819, PITTSBURGH, PA 15264-1819
PO BOX 641820, PITTSBURGH, PA 15264-1820
PO BOX 641821, PITTSBURGH, PA 15264-1821
PO BOX 641822, PITTSBURGH, PA 15264-1822
PO BOX 641823, PITTSBURGH, PA 15264-1823
PO BOX 641824, PITTSBURGH, PA 15264-1824
PO BOX 641825, PITTSBURGH, PA 15264-1825
PO BOX 641826, PITTSBURGH, PA 15264-1826
PO BOX 641827, PITTSBURGH, PA 15264-1827
PO BOX 641828, PITTSBURGH, PA 15264-1828
PO BOX 641829, PITTSBURGH, PA 15264-1829
PO BOX 641830, PITTSBURGH, PA 15264-1830
PO BOX 641831, PITTSBURGH, PA 15264-1831
PO BOX 641832, PITTSBURGH, PA 15264-1832
PO BOX 641833, PITTSBURGH, PA 15264-1833
PO BOX 641834, PITTSBURGH, PA 15264-1834
PO BOX 641835, PITTSBURGH, PA 15264-1835
PO BOX 641836, PITTSBURGH, PA 15264-1836
PO BOX 641837, PITTSBURGH, PA 15264-1837
PO BOX 641838, PITTSBURGH, PA 15264-1838
PO BOX 641839, PITTSBURGH, PA 15264-1839
PO BOX 641840, PITTSBURGH, PA 15264-1840
PO BOX 641841, PITTSBURGH, PA 15264-1841
PO BOX 641842, PITTSBURGH, PA 15264-1842
PO BOX 641843, PITTSBURGH, PA 15264-1843
PO BOX 641844, PITTSBURGH, PA 15264-1844
PO BOX 641845, PITTSBURGH, PA 15264-1845
PO BOX 641846, PITTSBURGH, PA 15264-1846
PO BOX 641847, PITTSBURGH, PA 15264-1847
PO BOX 641848, PITTSBURGH, PA 15264-1848
PO BOX 641849, PITTSBURGH, PA 15264-1849
PO BOX 641850, PITTSBURGH, PA 15264-1850
PO BOX 641851, PITTSBURGH, PA 15264-1851
PO BOX 641852, PITTSBURGH, PA 15264-1852
PO BOX 641853, PITTSBURGH, PA 15264-1853
PO BOX 641854, PITTSBURGH, PA 15264-1854
PO BOX 641855, PITTSBURGH, PA 15264-1855
PO BOX 641856, PITTSBURGH, PA 15264-1856
PO BOX 641857, PITTSBURGH, PA 15264-1857
PO BOX 641858, PITTSBURGH, PA 15264-1858
PO BOX 641859, PITTSBURGH, PA 15264-1859
PO BOX 641860, PITTSBURGH, PA 15264-1860
PO BOX 641861, PITTSBURGH, PA 15264-1861
PO BOX 641862, PITTSBURGH, PA 15264-1862
PO BOX 641863, PITTSBURGH, PA 15264-1863
PO BOX 641864, PITTSBURGH, PA 15264-1864
PO BOX 641865, PITTSBURGH, PA 15264-1865
PO BOX 641866, PITTSBURGH, PA 15264-1866
PO BOX 641867, PITTSBURGH, PA 15264-1867
PO BOX 641868, PITTSBURGH, PA 15264-1868
PO BOX 641869, PITTSBURGH, PA 15264-1869
PO BOX 641870, PITTSBURGH, PA 15264-1870
PO BOX 641871, PITTSBURGH, PA 15264-1871
PO BOX 641872, PITTSBURGH, PA 15264-1872
PO BOX 641873, PITTSBURGH, PA 15264-1873
PO BOX 641874, PITTSBURGH, PA 15264-1874
PO BOX 641875, PITTSBURGH, PA 15264-1875
PO BOX 641876, PITTSBURGH, PA 15264-1876
PO BOX 641877, PITTSBURGH, PA 15264-1877
PO BOX 641878, PITTSBURGH, PA 15264-1878
PO BOX 641879, PITTSBURGH, PA 15264-1879
PO BOX 641880, PITTSBURGH, PA 15264-1880
PO BOX 641881, PITTSBURGH, PA 15264-1881
PO BOX 641882, PITTSBURGH, PA 15264-1882
PO BOX 641883, PITTSBURGH, PA 15264-1883
PO BOX 641884, PITTSBURGH, PA 15264-1884
PO BOX 641885, PITTSBURGH, PA 15264-1885
PO BOX 641886, PITTSBURGH, PA 15264-1886
PO BOX 641887, PITTSBURGH, PA 15264-1887
PO BOX 641888, PITTSBURGH, PA 15264-1888
PO BOX 641889, PITTSBURGH, PA 15264-1889
PO BOX 641890, PITTSBURGH, PA 15264-1890
PO BOX 641891, PITTSBURGH, PA 15264-1891
PO BOX 641892, PITTSBURGH, PA 15264-1892
PO BOX 641893, PITTSBURGH, PA 15264-1893
PO BOX 641894, PITTSBURGH, PA 15264-1894
PO BOX 641895, PITTSBURGH, PA 15264-1895
PO BOX 641896, PITTSBURGH, PA 15264-1896
PO BOX 641897, PITTSBURGH, PA 15264-1897
PO BOX 641898, PITTSBURGH, PA 15264-1898
PO BOX 641899, PITTSBURGH, PA 15264-1899
PO BOX 641900, PITTSBURGH, PA 15264-1900
PO BOX 641901, PITTSBURGH, PA 15264-1901
PO BOX 641902, PITTSBURGH, PA 15264-1902
PO BOX 641903, PITTSBURGH, PA 15264-1903
PO BOX 641904, PITTSBURGH, PA 15264-1904
PO BOX 641905, PITTSBURGH, PA 15264-1905
PO BOX 641906, PITTSBURGH, PA 15264-1906
PO BOX 641907, PITTSBURGH, PA 15264-1907
PO BOX 641908, PITTSBURGH, PA 15264-1908
PO BOX 641909, PITTSBURGH, PA 15264-1909
PO BOX 641910, PITTSBURGH, PA 15264-1910
PO BOX 641911, PITTSBURGH, PA 15264-1911
PO BOX 641912, PITTSBURGH, PA 15264-1912
PO BOX 641913, PITTSBURGH, PA 15264-1913
PO BOX 641914, PITTSBURGH, PA 15264-1914
PO BOX 641915, PITTSBURGH, PA 15264-1915
PO BOX 641916, PITTSBURGH, PA 15264-1916
PO BOX 641917, PITTSBURGH, PA 15264-1917
PO BOX 641918, PITTSBURGH, PA 15264-1918
PO BOX 641919, PITTSBURGH, PA 15264-1919
PO BOX 641920, PITTSBURGH, PA 15264-1920
PO BOX 641921, PITTSBURGH, PA 15264-1921
PO BOX 641922, PITTSBURGH, PA 15264-1922
PO BOX 641923, PITTSBURGH, PA 15264-1923
PO BOX 641924, PITTSBURGH, PA 15264-1924
PO BOX 641925, PITTSBURGH, PA 15264-1925
PO BOX 641926, PITTSBURGH, PA 15264-1926
PO BOX 641927, PITTSBURGH, PA 15264-1927
PO BOX 641928, PITTSBURGH, PA 15264-1928
PO BOX 641929, PITTSBURGH, PA 15264-1929
PO BOX 641930, PITTSBURGH, PA 15264-1930
PO BOX 641931, PITTSBURGH, PA 15264-1931
PO BOX 641932, PITTSBURGH, PA 15264-1932
PO BOX 641933, PITTSBURGH, PA 15264-1933
PO BOX 641934, PITTSBURGH, PA 15264-1934
PO BOX 641935, PITTSBURGH, PA 15264-1935
PO BOX 641936, PITTSBURGH, PA 15264-1936
PO BOX 641937, PITTSBURGH, PA 15264-1937
PO BOX 641938, PITTSBURGH, PA 15264-1938
PO BOX 641939, PITTSBURGH, PA 15264-1939
PO BOX 641940, PITTSBURGH, PA 15264-1940
PO BOX 641941, PITTSBURGH, PA 15264-1941
PO BOX 641942, PITTSBURGH, PA 15264-1942
PO BOX 641943, PITTSBURGH, PA 15264-1943
PO BOX 641944, PITTSBURGH, PA 15264-1944