Geographic vs. Geographical
The distinction between “geographic” and “geographical” has been discussed before, but generally to conclusions of stylistic choice or difference between British and American English.
In my three years of studying linguistics, one thing I learned was that there are no true synonyms. Where two words seem to share meaning, they will always have some sort of difference in where they might be used. Whether the context is grammatical, social, or geographic, it will make a difference, however small. While this doesn’t particularly inform us of the distinction between “geographic” and “geographical”, I have come across the answer to this at some point in reading for my geography degrees.
I truly regret that I did not note the reference of this, and it was not the focus of the article I was reading. Nonetheless, I found the distinction to be very sound for prescriptive linguistics, though there are obvious disparities between prescribed and actual use.
This term is used to describe the geography of our Earth, the geography that most laypeople think of when they hear the word geography – things such as topography, topology, navigation, orientation, and mapwork. By this definition, your location in a place is geographic, not geographical. The sense of this word is tied quite closely to the physical world.
It is possible that AE (American English) only has this variant, though I am not American and so I will leave it to an American to confirm this. American leader in GIS chooses “Geographic Information Systems”, though GIS may be used for geographic or geographical analysis. This form is also found in the National Geographic Society (also famous for their magazine and television channels).
This word is more holistic in terms of gathering all the different aspects of geography, not simply maps and physical systems of rivers, rocks, and mountains. The word is used in more professional capacity because of this. Your location in space† might be geographical in light of this.
So, geographic factors are those such as altitude, aspect, wind-chill, latitude. Geographical factors include those of conventional “senior school geography” but also include social, political, economic, historical ones (to name just a few world systems).
Probably due to the shared adverb “geographically”, most people subconsciously use the backformation of “geographical” in everyday conversation. Perhaps it flows of the tongue more easily, though of course this might not be true for all nations and tongues.
† Place refers to a physical, measurable position or area, whereas space refers to a physical or non-physical space defined by other factors – for example, there might be nothing dangerous about being in a dark alleyway merely based upon place, but according to the associated aspects and threats, we learn to fear alleyways as spaces. Again, this language is not used by all of society, but can be evidenced in the language of professional geographers, artists, sociologists, and anthropologists.
Other discussions of these words: