The first parks to open were Paterson Great Falls National Historical Park and Eastside Park.
All visitors must adhere to strict social distancing precautions.
No groups, cookouts, or ball playing will be allowed.
"If people are not on their best behavior, if they are not social distancing, if they are not taking this situation seriously we will quickly reverse course, if there is a backslide then the parks will close," said Andre Sayegh, Paterson Mayor.
The two parks opened Friday at 6 and will close at 8 p.m.
If social distancing is followed, the mayor says other parks may reopen on a weekly basis.
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