July 1 will mark six months since it became the first U.S. state to legalize the cultivation, possession, and sale of recreational marijuana for adults 21 and older. State officials initially predicted that Colorado would rake in $184 million in pot-related tax revenue by June 30, 2015, and $150 million in the first year. 

Though tax revenue is steadily rising, numbers released by Denver-based pro–drug reform organization the Drug Policy Alliance now show the state's profits are lagging behind early projections.

"We now expect $40 million in tax revenue for the first year. We do expect as the industry gets larger that in 2015 and 2016 revenue will be higher than 2014," said Art Way, senior drug policy manager at the alliance. 

Colorado's Democratic governor, John Hickenlooper, called the recreational pot industry, still in its infancy, the "great social experiment of the 21st century."