Around 59,000 Bristolians have registered to vote by post in the forthcoming elections.
One in five Bristolians will vote by post
According to the city council, that is 20% of the city's electorate - and a massive rise from the 16,000 who used postal voting in the last general election.
Stephen McNamara, head of legal services and acting returning officer at Bristol City Council, gave three reasons for the increase.
"The availability of it, people becoming aware of it and the convenience," he said.
Responding to concerns about fraud, as highlighted recently in Birmingham, he said: "In Bristol, we keep a very close watch on everything that is happening.
"If we have the slightest suspicion, we go to the police immediately. I am confident that if there is any fraud, the people involved will be caught.
"But I want to emphasise, there is no evidence whatsoever that there is fraud in Bristol. Birmingham was a peculiar set of circumstances that don't apply here."
"Any system which encourages convenience for voters is a good thing," he added.
Mr McNamara said that Bristolians had now missed the chance to register to vote by post, but if people had concerns they should vote in polling stations or make sure they post their ballot themselves.