More than 300,000 people have applied to register to vote in 48 hours, according to government figures.
A total of 139,162 applications were submitted on Tuesday, followed by 177,105 on Wednesday.
This is well above the typical number for weekday applications, which has been averaging around 37,000 for the past month.
They are also the highest and second highest number of applications submitted on a single day this year.
Nearly two-thirds (65%) of applications were from people aged 34 and under, while just 4% came from those aged 65 and over.
A third were from people under 25.
The increase in the volume of applications should not be treated as direct evidence of an increase in the number of people able to vote.
At previous elections there have been applications from people below the legal age to vote or who are already on the electoral register.
The deadline for applying to register is Tuesday November 26.