So far in the Northeast, at least 51 deaths have been attributed to the storm. Overall, there have been at least 67 deaths across eight U.S. states related to Ida.
Here are the key developments:
President Joe Biden approved New York and New Jersey emergency declarations due to the storms and spoke on Ida's damage in the Northeast Thursday afternoon, citing that New York recorded more rain Wednesday "than it usually sees the entire month of September."
"People were trapped in the subways. But the heroic men and women of the New York Fire Department rescued all of them. They were trapped," Biden said.
He said he's made it clear to East Coast governors that the Federal Emergency Management Agency is "on the ground" and ready to provide assistance.
A flash flood emergency was declared for the first time in New York City as subway stations were turned into waterfalls and Midtown streets became rivers. The state of New York and New York City each declared states of emergency.
New York City Mayor Bill de Blasio said Thursday morning the death toll in the city was nine. That number rose to 13 by the evening.
"We saw a horrifying storm last night. Unlike anything we've seen before," de Blasio said. "Unfortunately the price paid by some New Yorkers was horrible and tragic."
At least 11 people who died in the storm died in their basement apartments, de Blasio said Thursday.
As of Friday morning, there are at least 8,000 residents without power across New York, according to PowerOutage.US. In a press briefing Friday morning Gov. Kathy Hochul said, "We’re well in excess of $30 million" in damage from Ida.
De Blasio also announced Friday the creation of a Climate Driven Rain Response Plan to improve the city's weather warning system. He said the city would also form a 30-day Extreme Weather Response Task Force to examine how the city can better prepare and respond to severe weather.
He said there may be more travel bans in the future and there'd be a focus on people living in basements including door-to-door warnings and a potential database of basement residents.
Most of the city's fatalities were in Queens.
Officers responding to a flooding condition at a partially collapsed building early Thursday in the borough found two people -- a 43-year-old female and a 22-year-old male -- unconscious and unresponsive inside, the NYPD said. The man was pronounced dead at the scene and the woman was taken to the local hospital, where she later died. "The investigation is ongoing and the Medical Examiner will determine the cause of death. The identification of the deceased is pending family notification," the NYPD said.
At a second flooded location in Queens, the NYPD said they found a 50-year-old man, a 48-year-old woman and a 2-year-old boy unconscious and unresponsive within the residence. They were all pronounced dead at the scene.
Also in Queens, police responded to a 911 call of a flooding condition and discovered a 48-year-old female, unconscious and unresponsive, within the residence. "The aided female was removed by EMS to Forest Hills Hospital where she was pronounced deceased," the NYPD said.
An 86-year-old woman also died in her Queens apartment due to flooding, police said.
On Thursday afternoon, the landlord at an apartment in Flushing called 911 to say there were three bodies submerged in a flooded basement, according to the FDNY.
"FDNY members rescued hundreds of people citywide during the storm, removing occupants from trapped vehicles on flooded roadways and removing New Yorkers from subway stations," department spokesman Frank Dwyer told ABC News.
After responding to a flooding incident in Brooklyn, the NYPD said officers found "a 66-year-old male, unresponsive and unconscious, within the residence." He was pronounced dead at the scene.
Meanwhile, in Westchester, County Executive George Latimer said Thursday that one person died after they were caught in a flash flood in their car. Three additional deaths in the county were later confirmed.
More than 100 people were rescued in Rockland and Westchester counties, officials said.
Hochul said during a Thursday morning briefing that her focus will be on flood prevention.
"Before we worried about coastal areas, now it's about what's happening in the streets, the drainage systems that need to be enhanced," Hochul said. "Because of climate change, unfortunately, this is something we're going to have to deal with with great regularity."
The inundating rainfall Wednesday evening broke records. Central Park reported a record for rainfall in one hour with 3.15 inches from 8:51 p.m. to 9:51 p.m., the National Weather Service reported.
New York issued a citywide travel ban just before 1 a.m. ET Thursday until 5 a.m.
"All non-emergency vehicles must be off NYC streets and highways," the city said.
Every subway line in the city was suspended, according to the Metropolitan Transportation Authority, due to so many flooded stations. De Blasio told ABC station WABC that people were being evacuated from subway cars stuck underground.
During the flooding, 835 subway passengers were rescued, the NYPD said Thursday.
There were also 69 water rescues, including 18 at the U.S. Open in Queens, police said. The U.S. Open had to pause one tennis match as the court was flooded Wednesday night -- despite there being a roof -- due to rain coming in the side of the stadium.
Nearly 500 cars were abandoned, police said.
The governor declared a state of emergency Wednesday within 14 counties "in response to major flooding due to Tropical Depression Ida," she said in a statement, while encouraging New Yorkers to "please pay attention to local weather reports, stay off the roads and avoid all unnecessary travel during this time."
Many New York communities are now grappling with water-logged apartments.
Ryan Bauer-Walsh, an artist who lives in Hamilton Heights, said his apartment on the fifth floor of one of New York City's Housing Development Fund Corporation cooperatives was inundated with rain.
"This is the second time in two months that the roof has caved in and they've been doing asbestos removal. Unfortunately, asbestos-contaminated water, we think, has come into our apartments," he told ABC News.
"My primary concern is with the infrastructure of the city," he said. "It's feeling a little hopeless ... especially as we get more and more of these massive storms."
In New Jersey, Gov. Phil Murphy quickly declared an emergency with 3 to 5 inches of rain falling per hour in some locations across the tri-state area.
"We will use every resource at our disposal to ensure the safety of New Jerseyans," Murphy tweeted. "Stay off the roads, stay home, and stay safe."
At least 27 people have died due to the storm in the state and at least four are still missing, Murphy said in a statement Saturday evening.
Most, if not all of the deaths, were due to flooding, he said, and no fatalities have been reported so far connected to tornadoes that touched down in South Jersey.
"I urge anyone who is in an area where flooding still persists to stay off the roads," Murphy said during a press briefing Friday.
Four residents of the Oakwood Plaza apartment complex in Elizabeth were found dead in the aftermath of the flooding, Mayor Chris Bollwage said in a press conference Thursday morning.
The victims were Rosa Espinal, 72; her husband Jose Torres, 71; their 38-year-old son, also named Jose Torres, and their neighbor Shakia Garrett, 33, city spokesperson Kelly Martins told ABC News.
Rescuers were checking the rent roll and going door-to-door through the entire complex to make sure no other bodies were found, a spokesperson for the mayor told ABC News. The complex is across from the Elizabeth Fire Department headquarters, which was inundated with 8 feet of water.
At least one person also died due to the flooding in Passaic, Mayor Hector Carlos Lora confirmed on Facebook Thursday morning.
The person was trapped inside their car, which was "overtaken by water," he said.
The mayor -- who declared a state of emergency in the city -- said that two other residents were reported to have been swept away by the water. The search continues for them.
"We have too many areas where the flooding has gotten so bad that cars are stuck and we have bodies underwater," Lora said in a video posted to Facebook Wednesday night. "We are now retrieving bodies."
Some 60 residents were receiving temporary shelter in City Hall, the mayor said Thursday.
Two people died from flooding in two separate incidents in Hillsborough and one person was found dead in a heavily damaged pick-up truck discovered in daylight in Milford, New York ABC station WABC reported.
Several homes were damaged in Mullica Hill, across from Philadelphia, due to a tornado that touched down. Three tornadoes were confirmed in New Jersey, most in the southern part of the state.
"Gloucester County has experienced devastating storm damage," the county said in a statement. "It is likely that multiple tornadoes have touched down within our communities. Our Emergency Operations Center is fully activated with multiple local, county, state, and regional partners assessing damages and deploying resources."
In Gloucester County, 20 to 25 homes were "completely devastated," and roughly 100 more sustained some damage, when a tornado ripped through Harrison Township, Wednesday, the mayor told ABC News.
Mayor Lou Manzo said the community is "blessed" that no one died and only one person had to go to the hospital, but the damage to property across the township is "extensive."
Fire and emergency personnel made "a few rescues" of people who became trapped after sheltering in their basement, according to the mayor.
There was also a "confirmed large and extremely dangerous tornado" located near Woodbury Heights, at about 6:30 p.m. and another "confirmed large and destructive tornado" over Beverly, near Trenton, at 7 p.m., according to the National Weather Service.
As the storm swept through the area Wednesday, a baggage area flooded and flights were grounded at Newark Liberty Airport.
"We're experiencing severe flooding due to tonight's storm," the airport's account tweeted. "All flight activity is currently suspended & travelers are strongly advised to contact their airline for the latest flight & service resumption information. Passengers are being diverted from ground-level flooded areas."
Cancellations were still commonplace Thursday afternoon out of Newark.
Early Friday, a Manville banquet hall went up in flames. It is one of three fires currently burning and inaccessible to firefighters due to the flooded roads.
The Saffron Banquet Hall on South Main Street exploded in flames at around 2 a.m., with residents from surrounding towns reporting hearing a loud explosion, the fire department said, adding that firefighters are unable to access the fire -- which appears gas-fed -- because it is surrounded by a flooded parking lot.
Two other homes, on Boesel Avenue and North Second Avenue, that caught fire Thursday afternoon continue to smolder Friday morning and are also inaccessible.
At least five storm-related fatalities have been confirmed in Pennsylvania.
Montgomery County had at least three deaths, the commissioner, Dr. Val Arkoosh, said during a press briefing Thursday morning.
One of those was an unnamed woman who died when a tree fell onto a home in Upper Dublin Township, according to Philadelphia ABC station WPVI.
A fourth Pennsylvania fatality, 65-year-old Donald Allen Bauer, of Perkiomenville, drowned inside his vehicle after it went into the Unami Creek in Bucks County, state police said in a news release.
The Chester County Coroner's Office announced a fifth storm-related death in the state -- Michael Nastasi, 51, of Downingtown, who is believed to have drowned.
Philadelphia Mayor Jim Kenney said it was "remarkable" no deaths were reported in the city connected to Ida during a Friday press briefing.
The Schuylkill River's flooding, which caused much of the destruction in the city, is now "below flood stage," Adam Thiel, chief of the Philadelphia Fire Department, said. The river crested at 16.5 feet, just below the 1869 record of 17 feet, he noted.
"We have not had a flood of this magnitude since the early 1900s," he said.
Officials said they're preparing for a recovery process that will take "months" after extreme flooding battered the city this week.
Randy Padfield, Pennsylvania's state emergency management agency director, estimated Thursday the number of water rescues to be in the "thousands" following catastrophic rain and flooding. In Montgomery County alone, officials responded to at least 500 calls, he said in a press briefing.
There were four confirmed tornadoes in Pennsylvania in Horsham Township, Bristol, Oxford and Buckingham Township, according to the NWS.
As of Friday morning, there are at least 25,211 residents without power.
A state trooper died after his vehicle was swept away in floodwaters in Woodbury, officials said in a press conference Thursday morning.
The trooper, identified as 26-year veteran Sgt. Brian Mohl, called for help around 4 a.m. and after a search was found and hospitalized with critical injuries. He died Thursday morning.
"Every line of duty death is heartbreaking and the loss of Sgt. Mohl is no different," Col. Stavros Mellekas, commanding officer of the Connecticut State Police, said in a statement. "He was outside, in the middle of the night, in horrendous conditions, patrolling the Troop L area. He was doing a job he loved and he was taken much too soon."
A 19-year-old male was found dead due to flooding at the Rockville Apartments in Montgomery County, police said in a news release. Officials received multiple calls for flooding at the home at 3:50 a.m. and 150 residents were displaced by floodwaters.
There were two confirmed tornadoes in Maryland, in Annapolis and Edgemere, that damaged property and downed wires and trees. No deaths or injuries were reported.
Multiple deaths have also been reported in the South.
In Louisiana, at least 12 fatalities have been reported, four of which resulted from carbon monoxide poisoning from the use of generators, according to Gov. John Bel Edwards.
Two deaths each have also been reported in Mississippi and Alabama.
ABC News' Will Gretsky, Alex Faul, Ahmad Hemingway and Melissa Griffin contributed to this report.