The use of marijuana has become legal in Washington, say sources. Now anyone aged 21 and over will be allowed to carry up to 1oz (28.4g) of cannabis, but smoking it in public will remain illegal.
Washington and Colorado both voted to decriminalise the drug, which remains illegal under US federal law, the BBC reports.
However, there will also be nowhere to legally purchase marijuana in the state for at least another year, the report said.
It also remains unclear how federal law enforcement agencies will deal with liberalisation of drug laws in Washington and Colorado, it added.
According to the report, any decision to crack down on states with liberal drug laws could affect Washington's plans to raise tax revenues from a licensed and controlled marijuana market.