Open the Thomas Guide to the Key Map section near the front of the book (pages vi and vii in most volumes)
Locate the desired city/neighborhood, printed in bold capital letters (smaller cities and neighborhoods will have smaller printing).
Find the nearest cross streets for the desired location, one running north to south, the other running east to west. Use a magnifying glass to read small print if necessary. If your city has many freeways, use them to locate your area, particularly where they intersect with other freeways or major highways.
Find the grid coordinate number for the desired area in large red print. This designates the Detail Map page number to focus the search. Turn to the page indicated.
Find the major intersection used for the Key Map on the Detail Map to narrow the search, and then locate the desired street. Street number gradations are marked in small red print; use these to locate your block.
