Where do the various BBWAA numbers come from?

Baseball election process is an imperfect game
Boston Globe, MA - Jan 8, 2007
Only writers who have been a member of the BBWAA for 10 or more years are allowed to vote for the Hall of Fame. Last year, 520 ballots were cast. ...

Ripken, Gwynn will get in Oneonta Daily Star, NY - Jan 9, 2007 Still, there are several other questions that can only be answered when the voting results of the 550-member BBWAA are announced today. ...***APSE site, says there are "825" members--see post below.

No Hall call for Rice
Boston Globe, MA - Jan 9, 2007
According to the Hall of Fame press release, a record 545 ballots, including two blanks, were cast by BBWAA members with 10 or more consecutive years' ...