Create a 27 Amendment legalizing marijuana

I propose creating a 27th amendment legalizing marijuana. By legalizing marijuana we could tax it, just like we do tobacco. We already know many people in the US buy and sell marijuana illegally so the smartest thing to do would be to tax it so the government makes money off of it. We could treat it just like alcohol with DWI or DUI and arrest any who are caught driving this way. Of course there has to be an age limit to buy it just like alcohol and that is why I say create a 27th Amendment so we can set the age limit at 27, just like the legal age to buy alcohol is 21. Instead of just ordinary farmers growing it where anybody could go steal it, allow the government to grow it, WITHOUT the use of harmful pesticides. This also has the capability to create more jobs.