Why isn't Marijuana legal in the United States??

Do You Know What Really Grinds My Gears?!...Marijuana

1. the cannabis plant
2. a preparation made from the dried flower clusters and leaves of the cannabis plant, usually smoked or eaten to educe euphoria
-The American Heritage Medical Dictionary

With all of the problems and stresses going on in the world, people are trying to find more and more ways to relax. It seems like sleeping, watching a movie, reading a book or listening to music just isn't doing the trick, anymore. It is because of this that people find themselves participating in activities such as social drinking or smoking. But, the problem which is the safest route to go...

...Here is where my issue come into play...why do we have dangerous "drugs" such as alcohol legalized in the United States, but Marijuana isn't?? I mean, I just can't wrap my head around this issue. Lets look at the side effects alcohol, tobacco and marijuana have on the human body.

Alcohol's Effects on the Human Body:
--Hangovers (headaches, nausea, vomiting)
--Weight Gain
--High Blood Pressure
--Cancer (2-4% of all cancer cases are due to alcohol)
--Liver Disease (can cause fatty liver, hepatitis, cirrhosis, and cancer of the liver)
--Alcohol Poisoning (breathing slow and skin gets cold and turns blue)
--Heart or Respiratory Failure (can lead to death)

Tobacco's Effects on the Human Body:
--Mouth and Lung Cancer
--Bronchitis
--Asthma
--Pneumonia
--Coronary Artery Disease
--Smaller Lungs
--Respiratory Illness
--Decreased Physical Fitness
--Unfavorable Lip Profile
--Potential Retardation in the level of Maximum Lung Function
--Death

Marijuana's Effects on the Human Body:
--Problems with Memory and Learning
--Distorted Perception (Sights, Sounds, Time, Touch)
--Trouble with Thinking and Problem Solving
--Loss of Coordination
--Increased Heart Rate

When it comes to alcohol and tobacco, there are many serious health problems that you risk experiencing such as multiple forms of cancer in various parts of the body, issues with the lungs and death. So, here's my problem...we have drugs that are legal to cause us serious bodily harm and even kill us, but we can't have drugs that are legal to help us chill and relax.

Now, I know what most of you are thinking...marijuana also has some side effects. Comedian Katt Williams jokes when he says that the only side effects of smoking marijuana are being, "hungry, happy, sleepy." The thing is, you'd either have to smoke an excessive amount of marijuana a day, you'd have to mix the marijuana with stronger drugs (i.e.--cocaine), or you'd have to drink while smoking excessive amounts of marijuana to experience these side effects. Also, these side effects - if they occur - usually only occur during the time period in which you're smoking.

Deaths due to Impairment:
--Alcohol: 30% of all accidents during the week (and 52% on the weekend) are due to drunk driving accidents; there are also records of hundreds of alcohol overdoses each year
--Tobacco: most causes of lung cancer death (men: 90%, women: 80%) are caused by cigarette smoke
--Marijuana: none reported

So, what grinds my gears is marijuana is the least harmful drug and it isn't legalized in the United States. Why do we have drugs such as alcohol and tobacco - which has been proven to kill - legalized in the United States and not marijuana which hasn't killed anyone or even harmed them?? Does anyone have an opinion or any possible answers??