When you upload a Census National Index Extract file, you will be given the opportunity to download the Aggregated Distribution file which is created from the National Index Extract file.
Alternately, if you are a Windows user, you can download a program that will convert a National Index Extract file into a an Aggregated Distribution File on your own PC.
The Aggregated Distribution file can be uploaded instead of the National Index Extract file if you wish to create distribution maps in a subsequent session. Because the Aggregated Data File is considerably smaller than the National Index file, it is much quicker to upload.
The format of the Aggregated Distribution File downloaded from this facility when you upload a National Index File is 'Tab delimited text', which uses TAB characters to separate the three fields in each record, as follows:-
Note that the TAB character is non-printing, and is represented by the in the above example. The 'Tab delimited text' format is convenient for loading into a spreadsheet for editing or further analysis.
The three fields in each record are the Surname, the abbreviation of the State, and the number associated with this state. When the Aggregated Distribution File is downloaded from this site, or created with the usdistag program which can be downloaded from this site, this number is the count of individuals with the Surname in the State. However, it could be some other figure, such as a population density (e.g. 0.000013) providing you calculate that figure and create an Aggregated Distribution File of your own.
In addition to the data, the file can also contain an optional title, which identifies the data in this set. The title appears on the first line of the file, thus:-
The title must appear on the first line of the file and it must be preceded by 'Title=' which identifies the record as the title record.
Creating Your Own Aggregated Distribution File
If you want to create distribution maps from a source of data other than the LDS 1880 US Census CDs, you can do so, but you will need to create your own Aggregated Distribution file.
As noted above, the file is a plain text file. You may use either TAB characters or commas (,) to separate the three fields in each record, as follows:-
The three fields in each record are:
The number can be a count of the number of people in the state with the surname, or any other meaningful measurement, such as density or frequency of the surname.
If your data are based on pre-1889 sources, then you will probably have state data for Dakota Territory, rather than the post-1889 states of North and South Dakota. In this case you should use the code DT for Dakota Territory, rather than the codes SD and ND. Take care that you use either DT or the state codes, ND and SD. If you do include DT and either of the codes ND or SD then the data for the two states North Dakota and South Dakota will not be plotted and will appear as Other in the Legend.
The easiest way to create your own Aggregated file is using a spreadsheet. Your worksheet should contain 3 columns, corresponding to the 3 fields in each aggregated record. When you have entered all your data save the file as a Text (Tab Delimited) file or as a CSV file. This file can then be uploaded for analysis, using the form on the Aggregated Distribution File Upload page. Some spreadsheets will enclose fields in double quotes ("). That's OK - the upload process strips any double quotes from the file being uploaded. If you are entering a title, it should be placed in cell A1, according to the rules specified above.
The table below shows the state abbreviations and the full names of the States.
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