Linked from
The 7 pages that link to January, each with the reason it gives.
MonthBroader topic: It exemplifies a fixed-length month in the standard civil calendar.
DecemberRelated: Moving the start of the Roman year to January left December as month twelve.
JulyCompared with: January shares July’s length but occupies the opposite end of the year.
OctoberRelated: Adding January before March shifted October from the eighth position to the tenth.
New YearRelated: The New Year observance occurs on the first day of this month.