The data, from the Department of Education, shows that, during the first year of the coronavirus pandemic, the number of children being looked after by councils in England hit a record high, as adoption processes slowed down.
Department for Education data shows 81,000 children were in care nationally in March – with 436 in Northumberland, the equivalent of 74 in every 10,000 young people in the area.
That was above the average national rate of 67 in 10,000 youngsters.
Figures show 172 youngsters in the area started to be looked after in 2020-21.
The 13 best beaches in Northumberland as ranked by Tripadvisor
Fun in the sun at Blyth beach
The 14 best beaches in Northumberland as ranked by TripAdvisor reviewers - and 6 stunners which didn't make it
Amble basks in the sunshine as heatwave hits
29 of the best places for Sunday lunch in Northumberland
The Local Government Association – which represents councils – said the "right level" of funding was needed to allow local authorities to prevent childrens’ services reaching a crisis point.
Anntoinette Bramble, of the LGA, said: "With spiralling demand on children’s social services and future cost pressures in children’s social care set to increase, councils still find themselves in the unsustainable position of having to overspend their budgets.
“Councils want to work with Government on a child-centred, pandemic recovery plan."
A Government spokeswoman said it was levelling up outcomes for vulnerable children through a regional recovery fund for children's social care, and also said councils were being given £4.8bn in funding to maintain frontline services.
She added: "To give all children the best start in life, we are also championing and investing in family hubs, with the aim of offering early help to families in need."