The US may likely do that first as china is always looking for cheap opportunities. The US is also in competiton with China as it has always accused China of flooding everywhere with take stuffs.
The first to legalize bitcoin is USA, even to make it easier for bitcoin users to do the transaction Bitcoin ATMs are provided in the USA in the amount of 2372 with the most placements in Los Angeles totaling 258 ATMs. As a developed country the USA is very open to the latest technology, including digital currency technology.