I'm non-US so I dont have any idea where to obtain detailed statistics - but does anyone have data about how many blacks in Colorado are in state/fed jail for pot compared to the whole US?

And as a side question: do private jails exist in Colorado, or is the jail system in state hands?

Federal jail would be a federal thing. There are federal prisons in CO, most notoriously the Supermax in Florence, but they don't put simple drug dealers in there. Federal arrests for pot in CO?

Most recent stats I found are 2010 http://www.ccjrc.org/pdf/2010_Colorado_Quick_Facts.pdf Latinos/as account for 17.1% of the population in Colorado, but 31% of the state prison population. • African-Americans make up 3.8% of Colorado’s population, but represent 19.4% of people in state prison. • Anglos are 74.5% of the state’s population, but only 46% of the prison population CO has private prisons too. I think that's nationwide these days, sadly.

Now bear in mind that pot has been de-facto legal in CO for about 4 years already. The Denver PD (largest city in the state) has been de-emphasizing pot enforcement for several years. There's been greater emphasis on other enforcement areas, like domestic violence and drunk driving.

Maybe you should do that research yourself before you spout off about how marijuana legalization in Colorado will drastically affect the racial ratios of imprisoned inmates here.