Q. How do I prepare a table for use within ArcMap?

There are five rules to remember.

(1) First, there can be only one header row (horizontal row at the top). ArcGIS will interpret the top row as the attribute names and the second row through the end of the table as the data contents. Often times tables may contain 2 or more rows at the top that help to define the contents of each attribute (vertical columns). Other times tables may contain no header row whatsoever. In both of these instances, the tables must be edited so there is one single header row before importing into ArcMap.

(2) Second, the header row can only contain letters, numbers, and underscores. All other characters (including space) will cause errors either when importing into ArcMap or when attempting to be made a permanent part of a feature class.

(3) Third, the header row may not begin with a number. For example, POP2010 is acceptable, but 2010POP may generate errors.

(4) Fourth, save your file in a format ArcMap can read. ArcMap can read a variety of file formats, but the most popular include Excel (.XLS or .XLSX), tab-delimited (.TXT), comma-delimited (.CSV), and dBase table (.DBF).

(5) Fifth, be careful how many characters you use in your header row. If you plan on integrating this table into a shapefile, all headers will be truncated to the first 10 characters.