The SSA has been tracking names statistics since 1879, though Social Security cards weren't often applied for at that time. True accuracy begins closer to the year 1937.
The following is taken directly from the SSA, with encouragement to post:
- Names are restricted to cases where the year of birth, sex, State of birth (50 States and District of Columbia) are on record, and where the given name is at least 2 characters long.
- With one exception, name data are not edited. For example, the sex associated with a name may be incorrect. Entries such as "Unknown" and "Baby" are not removed from the lists. The only exception to our non-edit policy is for names exceeding 10 characters in length. The data file we use is limited to the first 10 characters, so that a popular name such as Christopher lacks the terminal letter r. We fix obvious truncated names where possible.
- Different spellings of similar names are not combined. For example, the names Caitlin, Caitlyn, Kaitlin, Kaitlyn, Kaitlynn, Katelyn, and Katelynn are considered separate names and each has its own rank.
- When two different names are tied with the same frequency for a given year of birth, we break the tie by assigning rank in alphabetical order.
- Some names are applied to both males and females (for example, Micah). Our rankings are done by sex, so that a name such as Micah will have a different rank for males as compared to females. When you seek the popularity of a specific name (see "Popularity of a Name"), you can specify the sex. If you do not specify the sex, we provide rankings for the more popular name-sex combination.
- My own note: Names are tracked from March–February. For example, information that I refer to as coming from 2008 includes name information from March of 2008–February of 2009. Don't ask me why; that's just how it's done.
I write about rank so much because it's the best way to get a pulse on the popularity of a name. Without these statistics, analyzing names would be guesswork. There aren't many countries that publish government statistics on name popularity. Thanks, SSA!