The route of a new road tunnel under the Thames Estuary has been revealed.
The £6bn project will link the M25, near North Ockendon, Essex, with the A2 near Shorne, Kent, passing through greenbelt land.
The transport secretary said it would create more than 6,000 jobs and boost the economy by more than £8bn.
Adam Holloway, Gravesham's Conservative MP, said it was a "crazy idea" and "a disaster for the people of Dartford".
Under the plans, the new road will cross the A13 at Orsett and connect land east of Tilbury to land east of Gravesend.
A new road will then take traffic to the A2, near Thong, via the Western Southern Link.
Transport Secretary Chris Grayling said the new Lower Thames Crossing would also "reduce the burden on the busy Dartford Crossing".
A public consultation about the crossing started in January last year, with Highways England recommending option "C" as the favoured route.
However, opponents raised objections to the fact it would cut through greenbelt land, and its proximity to homes and schools.
Chair of Shorne Parish Council Robin Theobald told the BBC earlier that it was "not a day for celebrations".
Anti-option C campaign group, A Bridge Too Far, argued it would have a "detrimental affect" on the local area and Bob Lane, from the Lower Thames Crossing Association said: "Highways England have hoodwinked the government with their biased consultation. There wasn't a single mention of Option A."
There were originally three main ideas for a new crossing location:
- A - another crossing at the current Dartford Tunnel site and the Queen Elizabeth II Bridge.
- B - a route across the Swanscombe Peninsula, which was earlier scrapped.
- C - connecting the M25 to the A2 with multiple variants.
Bryan Sweetland, representing Gravesham on Kent County Council added it would take 10 years to build, by which time the old tunnels at Dartford would also need replacing.
Gravesham MP Mr Holloway, who also objected to the route, said: "It's a crazy idea. They [the Department for Transport] have no numbers on what portion of this traffic is national, and what is regional.
"It's also a disaster for the people of Dartford. We've had this once in a generation opportunity to fix the problem at Dartford, and it's been flopped."
However, according to the Department for Transport (DfT), the chosen option was picked by nearly 47,000 people who took part in a consultation.
A spokesman for the DfT said the C route had been "optimised" after the consultation, and moved slightly east to avoid people's homes.
The Ebbsfleet Development Corporation, which is building thousands of houses across north Kent, Eurotunnel, the Port of Dover, Kent Invicta Chamber and Dartford council leader Jeremy Kite (Con) all voiced their support for the decision.
Christian Brodie, of the South East Local Enterprise Partnership said: "This will strengthen the resilience of our UK and European connections - imperative as we now move towards Brexit."
Mr Grayling also promised £10m to help tackle traffic jams around the existing crossing.
Dartford's Conservative MP Gareth Johnson welcomed the decision, saying it was right "for Dartford but also for the whole country".
He added: "It would have been wrong to locate another crossing at Dartford and funnel more traffic in to the area and on to roads that can't cope as it is.
"I understand this decision may not be welcomed by residents in Gravesend but we will do what we can to ensure the impact on the environment is limited."
The Lower Thames Crossing is expected to carry 4.5 million lorries in its first year.