How do you classify travel guides?  It's been some time since I've had to do one.  The item in hand is a 2001 guide to the United States. 

Start by looking for travel guides in the Relative Index.  You will find the number 910.202.  The caption is "World travel guides," so this isn't the number you are seeking, but the notes include the following add instruction:

"Class guides to specific continents, countries, localities in 913-919, plus notation 04 from table under 913-919." 

On to 913-919, where you'll be instructed to "add to base number 91 notation T2--3-T2--9 from Table 2" then add further according to the add table there. 

You probably know that the Table 2 number for the United States is 73.  So your number will begin with 917.304. 

Regarding the period covered by the guidebook, the add table at 913-919 has an entry "041-049 Historical periods."  It reads in part, "for United States historical periods, add to 04 the numbers following 973 in 973.1-973.9, e.g., travel in United States during the Nixon administration 917.304924." 

The print edition, DDC 21, was published in 1996, so the 973.9 numbers stop short of the current administration.  However, the new number, "973.931 Administration of George W. Bush, 2001-" was posted on the New and Changed Entries section of this web site last December.  (Click here for this quarter's New and Changed Entries.)  The number also appears in the tip Dewey Decides Again. 

The number for a 2001 guidebook to the United States is, therefore, 917.304931. 

Last revised: 25 January 2004