What exactly is the ranking system of Judo in America? I thought it was Light blue, white, brown, black, white and red, then red. However, at the place where I train there is no light blue only white, then I am assuming brown, then black etc. The thing that really confuses me is that apparently Joe Rogan has a green belt in Judo, but to my knowledge there is no green belt so I am really confused. Can anyone clear this up? THANKS!
While rank structures may vary a fairly typical structure would be as follows:
White
Yellow
Orange
Green
Blue
Purple
Brown
Black
In some instances green, blue, purple or brown may be absent or occasionally purple will outrank brown but the preceding structure is a reasonable guideline. 
When I trained years ago that was basically the syllabus we used minus the purple belt.
I will give you the exact rank for adults along with the names of each rank: In the US the kids/juniors use colors yellow,orange and purple. When we had Canadian visitors the adults also wore Yellow/Orange. The name of your rank is just as important as your belt color.
6th grade rokyu -white
5th grade gokyu - green
4th grade yonkyu - blue
3rd grade sankyu - brown
2nd grade nikyu-brown
1st grade ikkyu - brown
1st degree shodan -black
2nd degree nidan- black
3rd degree sandan-black
4th degree yodan - black
5th degree godan - black
6th degree rokudan -red/white
7th degree shichidan -red/white
8th degree hachidan -red/white
9th degree kudan -red
10th degree judan- red
In the U.K.
Red
White
Yellow
Orange
Green
Blue
Brown
Black
5th Dan and above RED / White
I am still confused. At my school there only appear to be white belts, brown belts and black belts and I have yet to see any of these colors. I look at different sources, but every source I come across is different.
We don't use purple belt but it is similar to an above post:
White
Yellow
Orange
Green
Blue
Brown
Black
5th Dan and above RED / White
lots of correct answers
i use
white
yellow
green
brown
brown
brown
black
many places will skip either yellow or green or both
problem is in the US there are at least 3 official judo organizations
i believe at the place i train its white,yellow,orange,green,brown,black but not positive
JMH - I am still confused. At my school there only appear to be white belts, brown belts and black belts and I have yet to see any of these colors. I look at different sources, but every source I come across is different.
All belt colors below black are "optional," really. Most rank awarding bodies allow the instructor to choose whether or not to use the color belts.
Many old school dojos (and most I've known in Japan) do not have ANY colored belts below black. Some will have purple or brown for the kids due to age restrictions on black belt testing, but that's it. I think I can count on my hands the number of colored belts I've seen in the past 7 years.
JMH- that is why I gave you the name of each rank along with the belt color. If you are white belt then your rank is Rokyu. Going forward your next rank/promotion will be Gokyu. It appears from the answers there are different belt colors for Gokyu, Yonku, Sankyu, Nikyu Ikkyu(brown). When we have local tounaments the application asks your belt color and rank name because we know there are different belt color systems( USJF,USJA,Canadian) out there but not different rank names. Novice ranks are Roykyu,Gokyu,Yonkyu. Advancd ranks are Sankyu, NIkyu,Ikkyu, Shodan and above. Sometimes there is Sankyu,Nikyu competitive bracket so they don't have to fight in the advanced division. Hope this helps.
Depends on organization.
The club where I practice Judo is USJA and uses the Yellow, Orange, Green and then 3 grades of Brown before Black. The instructor has already indicated he would like to move me up from White (I assume to Yellow). It's been 4 classes and I feel like I have so much more technical stuff that I want to learn before doing anything Belt wise... Oh the joys of starting over in another MA!
The provided information above covers all the different belt color systems (US) but understand what your rank is not by belt but by rank name. FJJ828- that is unusual for a promotion after 4 classes. One thing I notice in judo is it promotes too fast (in my opinion )in general).
Think so? I have a 4th degree in TKD from years ago and they promoted fast. Mostly because every rank is kind of ready to go to the next rink. Everything you learned in the color belt ranks was to set up the next promotion/grading. Most Judo schools I have seen don't promote that fast but I have only studied at a few.
Does the USJA still use the red and black belt?
I would tend to agree. In my opinion, my Judo skills are not great but I do have a fundamantal grasp of the throws as I learned them in Traditional JJ and then later in BJJ. My weakness is my gripping. In any case, I am enjoying the practice and the idea of "starting over" after so long in BJJ.