Zip codes in some Eastern states begin with the number 0. Spreadsheets such as MS Excel think it's irrelevant to display zeroes at the beginning of a numeral, and so they will not display the full zip code, even if the zero does exist in the list.

Solution:

When wishing to view data with leading zero zip codes in Excel, the best thing to do is import the file into Excel with all fields marked as "text".

1. Make sure that the name of your file ends in ".txt". If need be, rename the file's extension. To do this, find the file where you saved it (usually My Documents), right click on it, and choose Rename.
2. In MS Excel, click File/Open and change the Files Of Type to "All Files". Browse to the location of the file. Double-click the desired TXT file.
3. An Import wizard will display. The steps are
   1. Delimited
      
   2. Comma and/or Tab
      
   3. Highlight all columns at the bottom (scroll to the right, hold down the shift key and click on the rightmost column) and choose Text for the Column Data Format. Click Finish.
4. Check to see that the zeroes are there, and save the file in Excel format (.xls).