Right before I ran a database migration to create the tables to house the lat & long information for US Cities I realized that longitude and latitude strings could never be over 100 characters long. Instead of blindly using 24 characters or even 20, I wanted to know what I was working with for US Cities ONLY.The small gist below shows the very small range of length for the lat & longs.
https://gist.github.com/2698035
spoiler: It's between 9-11 for latitude, and 11-12 for longitude