Customers have bought $12.1 million of legal recreational pot since July 8, the day licensed stores first opened for business, according to Washington’s State Liquor Control Board. Total sales doubled in August to $6.9 million from $3.2 million in July. Meanwhile, monthly tax revenue climbed to $1.75 million from around $805,000.

Rising pot sales and the associated tax revenue is good news for supporters of pot legalization who are eager to point out the communal benefits of legal marijuana. It also may influence voters in other states like Alaska and nearby Oregon, where voters will soon decide whether to hop on the recreational marijuana bandwagon.

What’s more, data released for the beginning of September shows sales could grow again this month. During the first eight day of September, the state’s recreational pot stores have had $1.9 million in sales – or on pace for around $7.1 million for the entire month. That would translate into $1.8 million in taxes.

An obvious factor behind the sales growth is the fact that more stores are opening across the state. There were only two-dozen approved retail shops in the when recreational sales kicked off in July, but that number has since grown to more than 50 stores – with more on the way as officials grants additional licenses to some of the thousands of applicants.

It also didn’t hurt that the comparison between the two months was a bit skewed. August’s figures included sales for the entire month while July’s only included three weeks of business.

Another reason for the booming sales is that stores are now less likely to run out of marijuana supplies. Many did so regularly early on but have since mostly cleared up their supply-chain issues. The Seattle Post-Intelligencer reported this week that the more than 200 licensed growers have filled the state’s cap of 2 million square feet of legal growing space, allowing production to finally keep up with demand.

Of course, Washington’s sales still pale in comparison to those in Colorado, where there are almost 200 fully-licensed recreational shops in the state, which was the first to allow recreational sales at the start of this year. Colorado Department of Revenue reported this week that it collected $2.97 million in taxes on recreational pot sales (which are taxed at 10% in that state) for the month of July, indicating $29.7 million in sales that month.

As Time reported this week, Colorado’s recreational pot sales have finally surpassed those of the state’s medical marijuana shops, which outnumber the recreational stores by more than 2 to 1.

The fact that more consumers are buying recreational marijuana in Colorado is good news for those who supported the end of cannabis prohibition in that state. As Time pointed out, luring customers from medical dispensaries, not to mention black market dealers, has been an important step toward success for the legalization experiment in Colorado. (That situation in Colorado also offers up a stark contrast to Washington, where the medical marijuana industry is not nearly as developed.)

Meanwhile, as Washington tries to keep up with Colorado in terms of recreational marijuana sales, the state may also eventually lose sales in areas near the Oregon border. The Post-Intelligencer notes that stores in Vancouver, Washington – just across the Colombia River from Portland – have been especially strong, but that could all change if Oregon residents vote on a November ballot initiative to legalize recreational marijuana sales in that state as well.