The 1990 Zip Code by State file is comma separated values, ASCII text, one 
record per line. The field/record layout is as follows: 

Field 1 - State Fips Code 
Field 2 - 5-digit Zipcode 
Field 3 - State Abbreviation 
Field 4 - Zipcode Name 
Field 5 - Longitude in Decimal Degrees (West is assumed, no minus sign) 
Field 6 - Latitude in Decimal Degrees (North is assumed, no plus sign) 
Field 7 - 1990 Population (100%) 
Field 8 - Allocation Factor (decimal portion of state within zipcode)