TL;DR
Arc is Circle's Layer 1, live on mainnet since September 16, 2026, with USDC as the gas token instead of a volatile native asset.
Across has supported Arc since day one. Arc is chain 5042, with a SpokePool and MulticallHandler deployed and live on the Swap API.
Across quotes USDC routes into Arc from seventeen chains, including Ethereum, Base, Arbitrum, Optimism, Polygon, Avalanche, BNB Chain, Linea, zkSync, Unichain, HyperEVM, and Monad. Routes out of Arc are live too.
Fills land in roughly two seconds because relayers front their own capital on the destination and settle with the source chain afterward.
The USDC that arrives is the balance that pays for gas on Arc, so there is no second token to go find.
Every new chain hands you the same first problem. You arrive holding the asset you wanted and none of the token you need to move it. Arc deletes that problem by making them the same thing. Gas on Arc is USDC, so when you bridge USDC to Arc, the balance that lands is the balance that pays the fee on your next transaction. Across has been live on the chain since launch day, which makes the whole trip one hop with nothing to reconcile at the other end.
Arc Runs on Dollars, Not a Volatile Gas Token
Circle launched Arc mainnet on September 16, 2026. It is an EVM Layer 1 built for payments, FX, and institutional settlement, running Malachite BFT consensus over a permissioned validator set that includes BlackRock, DTCC, ICE, Mastercard, and Visa. Finality is deterministic and sub-second, with no reorg risk. Circle has said the network moves to proof of stake in 2027.
The design choice that matters most for anyone arriving from another chain is the gas token. Arc does not have one in the usual sense. Fees, native balances, and native transfers are all denominated in USDC.
Arc exposes that USDC through two interfaces over a single balance. The native interface carries 18 decimals and handles gas accounting, msg.value, and native transfers, the way ETH behaves on Ethereum. The ERC-20 interface lives at 0x3600000000000000000000000000000000000000, carries the familiar 6 decimals, and handles application-level transfers and approvals. A precompile keeps the two in sync at a fixed 1e18 to 1e6 ratio. There is no wrapping step and no wrapped version to hold.
For a user, that collapses two balances into one. For a developer porting a contract, it is a real assumption break: balanceOf truncates the last twelve decimals, so dust below 1e-6 USDC exists in the native balance and does not show up in an ERC-20 read. Circle's docs are direct about this, and it is worth handling before you ship.
Arc also supports EURC and USYC natively, and Circle StableFX runs cross-currency settlement across roughly twenty additional local stablecoins on the chain.
Across Was Live on Arc From Day One
Arc is chain ID 5042 on Across. The SpokePool sits at 0x9b4A302A548c7e313c2b74C461db7b84d3074A84, with a MulticallHandler at 0xA07480456C4EbaD7626e4FdF4a180709E238547b, and the chain is live on the Across Swap API alongside the other supported networks.
Across quotes USDC into Arc from seventeen origin chains. Ethereum, Base, Arbitrum, Optimism, Polygon, Avalanche, BNB Chain, Linea, zkSync, Unichain, World Chain, Ink, Soneium, HyperEVM, and Monad are all live routes, and the bridge runs in both directions: USDC out of Arc to Ethereum, Base, and the rest of the network is available from the same interface.
Because the Swap API handles the origin-side swap, you do not have to be holding USDC to start. Bring ETH on Arbitrum or any other supported token, and Across swaps it on the origin chain and delivers USDC on Arc in one transaction.
How to Bridge USDC to Arc
Open across.to/arc-bridge and connect your wallet.
Pick your origin chain and the token you are sending. Across quotes the route and shows the output amount and fee before you sign.
Confirm the deposit on the origin chain. You pay gas once, there.
Watch the fill on Arc. Expect it in a few seconds.
Fills Land Before the Source Chain Finalizes
A conventional bridge waits for the origin chain to finalize before releasing anything on the destination. That wait is the whole delay, and on Ethereum it is measured in minutes.
Across inverts the order. You submit an intent describing the outcome you want, and a relayer fills it on the destination chain using its own capital, immediately. Settlement happens afterward, on the protocol's schedule rather than yours. The Dataworker aggregates every fill into a single bundle, relayers are repaid roughly every 1.5 hours, and bundle proposals are posted with a bond and accepted unless a challenger disputes them. The UMA Optimistic Oracle on Ethereum secures that step. One honest actor is enough to reject a bad bundle.
That architecture is why the number on Arc is two seconds rather than two minutes, and it is the same architecture that has moved more than $39 billion with no user funds ever lost.
Builders Get the MulticallHandler on Arc Too
The MulticallHandler is deployed on Arc, which means a transfer into the chain can carry instructions with it. The destination SpokePool calls handleV3AcrossMessage() on the handler, and the handler executes your encoded calls atomically with the fill. Approve and deposit into a lending market, route the output to a different recipient, or hand the funds to your own contract, all inside the same transaction that brings them across.
On Arc this composes unusually cleanly, because the token your user receives is also the token their next transaction spends. There is no gas top-up step to design around. Contract addresses and integration details are in the Across chains and contracts reference.
There Is Already Somewhere to Go
Arc launched with more than 100 applications live. Aave and Morpho are running lending markets. Uniswap and 1inch handle spot. Robinhood, Dinari, and edgeX cover trading surfaces, and Circle StableFX provides the FX layer underneath. Exchanges including Coinbase, Binance, and Kraken support the chain, as do MetaMask, Phantom, Ledger, and Rainbow on the wallet side.
Liquidity showing up on a new chain usually lags the chain itself by a quarter. Arc skipped that part, which is the argument for having a fast route in on the day it opened.
On most chains you bridge one token and then go hunting for another before you can spend it. On Arc the dollar that arrives is the dollar that pays the fee, and Across puts it there in about two seconds.
