The Police Federation has warned that officers no longer have the resources to effectively combat drugs.
Northamptonshire Police carried out 1,563 drug seizures in Northamptonshire in 2017-18 – down from 2,631 in 2013-14, when they peaked.
It means there were 2,109 seizures for every million people in the area, compared to an average of 2,199 for England and Wales.
The most commonly confiscated drug was cannabis, with 2,419 plants, 45kg of herbal cannabis and 0.9kg of cannabis resin seized.
Cocaine (0.4kg), crack (0.3kg) and morphine (301 doses) were also confiscated in significant quantities.
England and Wales’s 43 police forces and Border Force carried out 136,000 seizures during 2017-18.
It was a drop of 2% on the previous year, and the lowest annual number since 2004.
The Police Federation of England and Wales said that erosion of stop and search powers were hampering the fight against drugs.
Simon Kempton, operational policing and drugs lead, said: “It is no coincidence that we have lost nearly 22,000 police officers since 2010 – it’s a simple fact that you just can’t do more with less.
“Along with a pinch on resources against a background of austerity, drugs squads have been disbanded, and those that are still operational are having to multi-task and focus on other things as well such as different organised crime gangs.
“Chief Constables have had to re-evaluate their resources and choose where to put their boots on the ground.”
Since peaking in 2008-09, the number of recorded drug offences across England and Wales has decreased by 44%.
A Home Office spokeswoman said: “Drugs can devastate lives, ruin families and damage communities.
“The Government is taking this seriously and is committed – through three key strategies backed by millions of pounds of funding – to tackling the illicit drug trade, protecting the most vulnerable and helping those with a drug dependency to recover and turn their lives around.
“The Home Secretary also recently announced a major review of drugs, which includes a focus on the illicit market.”