Cannabis is illegal at the federal level in the U.S. That makes it difficult for Canadian companies to expand in the market. But that hasn’t stopped domestic players from spreading their roots. Even with a limited legal market, U.S. cannabis companies are thriving as state legalization keeps ramping up. Among them, Illinois-based Cresco Labs (OTC: CRLBF), with a market cap of $2.1 billion, is shining its way through the list of top contenders in the cannabis space.