Launched by the Centre Consortium in October 2018, USD Coin reached a $1 billion market cap in 21 months.
Source: https://cointelegraph.com/news/coinbase-and-circle-backed-stablecoin-usd-coin-breaks-1b-market-cap
Coinbase and Circle-Backed Stablecoin USD Coin Breaks $1B Market Cap
July 3, 2020
CoinTelegraph