Windsor's unemployment rate jumped another 3.8 percentage points last month as the local economy shed 16,400 jobs.
At 16.7 per cent, it is the highest in Canada.
Statistics Canada released its Labour Market Survey on Friday for May.
It also suggested the Labour Participation Rate fell 2.4 percentage points to 54.4 per cent. That measures all those who are employed or unemployed but looking for a job.
Across Ontario, the bleeding of jobs slowed in May. A total of 65,000 jobs were lost, compared to 403,000 in March, and 689,000 in April. The provincial unemployment rate was 13.6 per cent, up 2.3 percentage points from the month before.
Nationally, Statistics Canada said employment grew by 290,000 net positions, 219,000 of which were full-time. However, more people joined the search for work driving the jobless rate across Canada up to 13.7 per cent, 0.7 percentage points higher than April.
"The unemployment rate was 13.7 per cent in May, the highest rate recorded since comparable data became available in 1976," said Statistics Canada. "In February, the unemployment rate was 5.6 per cent. It increased to 7.8 per cent in March, and 13 per cent in April."
The National Labour Participation Rate increased 1.6 percentage points in May to 61.4 per cent, demonstrative of those who joined the labour market. It was still well below the pre-COVID-19 rate in February when it was 65.5 per cent.
The number of self-employed workers changed little from April, but 42.9 per cent of those worked less than half of their usual hours because of the COVID-19 pandemic. That is lower than the month before when 50.2 per cent said they were working less than half of their usual hours.
The survey also found fewer Canadians are working from home. In May, eight million Canadians worked at least half of their usual hours somewhere other than their house. That's an increase from 7.2 million in April.
About 4.9 million Canadians said they were working from their home.
The survey, taken the week of May 10, surveyed 40,000 households across the country.