Availability of drugs would not make drug users go live there. That's just ridiculous.
And just because cocaine was "legal" at one time doesn't mean everyone used it. In fact very few people even knew what cocaine was.
Opium was once legal as well for a time in the UK. However, its use as a pharmaceutical panacea and exotic recreational drug became epidemic throughout all of British society.
Perhaps you should read up on how opium nearly destroyed entire nations before you daydream about drugs being "legalized". Legalized pot would be a repeat of what legal opium was in India and the UK, since both make people extremely lazy.
I won't argue this for one second, but until people change their beliefs, no amount of regulation and spending of my money will stop them from being idiots. There are many many epidemic problems in America that will not be quelled by a federal law, such as porn. Sexual addiction in America is out of control, but I don't want my tax dollars spent on trying to wipe it out, because the same sex addict will find something to ruin himself with no matter what kind of money I throw at the problem.
Like I said before, if certain states want to crack down on drugs hardcore then that would discourage most of the drug users from living in those states far more than current regulation does.
I took your suggestion. Here's what the usdoj website says:
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"By 1900, about one American in 200 was either a cocaine or opium addict." [that's 0.5% - ken]
--http://www.usdoj.gov/dea/demand/speakout/06so.htm
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"There were an estimated 980,000 hardcore heroin addicts in the United States in 1999, 50 percent more than the estimated 630,000 hardcore addicts in 1992."
http://www.usdoj.gov/ndic/pubs07/794/heroin.htm
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"Among those using cocaine in the United States during 2000, 3.6 million were hardcore users who spent more than $36 billion on the drug in that year."
--http://www.usdoj.gov/ndic/pubs07/794/cocaine.htm
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The US population in 2000 was about 280,000,000. So the combined addiction rate was about 1.6% in 2000 vs 0.5% in 1900.