The standard columns are the same for each file in the directory as they are physical characteristics of the grid cells and not dependent on the monthly variable in the file. Following this are twelve columns containing the data by month so each line of the file begins with the appropriate gridpoint and ends with the data value for December. Information on the format of the site files and how to find data for specific locations is available here . Gridpoint number starts at 1 in the far north west corner of the bounding rectangle and finishes at 5520 in the south east. There are 115 gridpoints across the domain and 48 down.
Gridpoint position is shown in the diagram below.
Most of these points are around the edges of the map but some interior cells are excluded such as Great Salt Lake or river inlets. This means that each file is in fact only 3261 lines long and that the gridpoint number is not sequential. This is also a description of the major vegetation type to be found in each gridcell. There are several cases where the grid cell was split very evenly between states so that some of the allocations are ambiguous.