While local currencies—issued by municipal governments, businesses or even individuals—have long existed, they’ve been undergoing a resurgence thanks in part to the economic crisis and rising income inequality. A local currency can help to mitigate the impact of a troubled economy, potentially stimulating growth in a community by increasing demand for local goods while keeping money from flowing out of the area. That was the impetus behind the creatively named COjacks, a Colorado-wide currency launched by two men in the state last month. Nearly 100 businesses have thus far agreed to accept it—consumers can pay for 10-30 percent of a purchase with the currency—according to Colorado Public Radio.

Other local U.S. currencies include Equal Dollars in Philadelphia, BerkShares in the Berkshire region of Massachusetts and Ithaca Hours, introduced in 1991 to help buoy New York city’s economy during a recession and keep residents employed. Today, more than 900 participants accept Ithaca Hours as payment. Many more examples can be found around the world. For instance, dozens of local currencies circulate in Brazil. In the U.K., examples include the Brixton Pound and Bristol Pound—both of which recently launched mobile payment apps—and the city of Hull’s HullCoin, a digital cryptocurrency launched earlier this year that functions like bitcoin.

With bitcoin and other cryptocurrencies driving people to think about currency in new ways, watch for local forms of money to gain traction in more communities around the world.