Why isn't marijuana legal?

I don't know but it should be.
It is not legal because it is too hard to tax. Many people know how to grow their own and enforcement would be nearly impossible for taxation. You would also have too many people thinking they are 'okay' to drive or operate machinery.
The answer to that question can be easily answered in the book, 'The Emperor wears no clothes'

If you are really interested in the reason why, I suggest you check it out.
becuse the gov cant tax it any one can grow it
probably because th gov't can't find a way to regulate and tax it. Boy, I'd hate to see what car insurance rates would rise to if weed was legalized though! And many, many people wouldn't even care because they would be stoned out of their minds...lol
its legal in alaska where I am moving on Friday! who hooo!
I have no idea..maybe its because of the government and they are using it for there own personal use .


Answers:
Originally it was based apon Racism, Fear, Protection of Corporate Profits, Yellow Journalism, Ignorant, Incompetent, and/or Corrupt Legislators, Personal Career Advancement and Greed - And this was BEFORE 1930.
Nationally Harry J. Anslinger is responsible for using public office for his personal gain. And in the process promoted racism along with lies and sheer fantasy with such gems as (and these are actual quotes!):

'There are 100,000 total marijuana smokers in the US, and most are Negroes, Hispanics, Filipinos, and entertainers. Their Satanic music, jazz, and swing, result from marijuana use. This marijuana causes white women to seek sexual relations with Negroes, entertainers, and any others.'

Reefer makes darkies think they're as good as white men.'

'Marihuana leads to pacifism and communist brainwashing'

'You smoke a joint and you're likely to kill your brother.'

'Marijuana is the most violence-causing drug in the history of mankind.'
--- WHEW!
And to sum it up - this all happens after Prohibition Failed.
So called legislating morality rarely has NOTHING to do with MORALITY. It is just used so somebody can gain personally. So a government official can gain more power, money and/or prestige.

Otherwise instead of adding money to the DEA's and related agencies coffers we could use the money instead for Healthcare, Education, Job Training, Short and Long Term Disability coverage, help for the homeless, take care of our Vetrans to start - How many people would that keep from needing drugs as an 'escape' in the first place. And then there is the money from taxing it!
And if nothing else - why not a 2 year test of legalization - if it doesn't seem to be going in the right direction then it would at least put a squeeze that foreign drug cartels have never had - Only let AMERICAN COMPANIES distrubute and only allow it to be made from American Crops - Well there goes the demand for these types of goods from Mexico/South America.
Because there would be certain activist groups (probably churches) that would have a huge problem with this and there would be a mini crisis until they shut the eff up... And the government doesnt want to deal with that... plus theres issues of taxing...
I say within the next 50 years marijuana will be legalized...
A ton of reasons, but mostly because those against the legalization of marijuana have taken their stand on misguided moral reasons; although they use nonfactual arguments such as 'medical findings, gateway drug, crime, etc.' to disguise their true colors.