Arc Mainnet, T-minus 12: what actually happens on September 16

Circle has confirmed September 16 as the public mainnet date, moving Arc from its private mainnet — where 100+ institutions and builders have been operating — into production for everyone.

What it means

Three things change on the 16th. The network's real parameters — mainnet chain ID, RPC, explorer — get published, and wallets can connect to the production chain for the first time. Real USDC starts moving: value on Arc stops being test money from a faucet and becomes actual dollars bridged in via Circle's transfer protocol. And deployment opens up — the apps that have been waiting, including Uniswap, Aave, Morpho and Aerodrome among the named day-one cohort, go live for the public, and new tokens and contracts can be deployed by anyone.

Just as important is what does not change. No ARC token appears — the network launches with USDC as gas, exactly as designed, and any token claiming otherwise that day will be counterfeit. Your testnet balances do not migrate; test dollars stay test dollars. And the institutions do not arrive on the 16th — they are already there, which is arguably the real story of this launch: by the time the public gets in, BlackRock, Visa and DTCC have been operating the rails for months.

Expect the loudest day of Arc's life on every channel, and calibrate accordingly: the launch itself is infrastructure going public, not a trading event. The people best positioned that day are the ones who already know how the chain works.

One lesson

If you are starting from zero, learn what Arc is before mainnet day rather than during it.