MELBOURNE BEACH, Fla. — Hurricane Matthew marched toward Florida, Georgia and the Carolinas and nearly 2 million people along the coast were urged to evacuate their homes Wednesday, a mass exodus ahead of a major storm packing power the United States hasn’t seen in more than a decade.

Matthew was expected to be very near Florida’s Atlantic coast by Thursday evening.

At least 16 deaths in the Caribbean have been blamed on the storm, with heavy damage reported in Haiti.

The storm was forecast to scrape much of the Florida coast and any slight deviation could mean landfall or it heading farther out to sea. Either way, it was going to be close enough to wreak havoc along the lower part of the East Coast, and many people weren’t taking any chances.

In Melbourne Beach, near the Kennedy Space Center, Carlos and April Medina moved their paddle board and kayak inside the garage and took pictures off the walls of their home about 500 feet from the coast. They moved the pool furniture inside, turned off the water, disconnected all electrical appliances and emptied their refrigerator.

They then hopped in a truck filled with legal documents, jewelry, and a decorative carved shell that had once belonged to April Medina’s great-grandfather and headed west to Orlando, where they planned to ride out the storm with their daughter’s family.

‘‘The way we see it, if it maintains its current path, we get tropical storm-strength winds. If it makes a little shift to the left, it could be a Category 2 or 3, and I don’t want to be anywhere near it,’’ Carlos Medina said.

In Fort Lauderdale, six employees at a seven-bedroom Mediterranean-style mansion packed up for an evacuation fearing any storm surge could flood the property. The homeowners planned to move to another home they own in Palm Beach that’s further from the water. Two Lamborghinis and a Ferrari had been placed inside the garage, but employee Mae White wasn’t sure what they would do with a Rolls Royce, Mustang and other cars still parked in the driveway.

‘‘This storm surge. It’s scary,’’ White said. ‘‘You’re on the water, you've got to go.’’

The last Category 3 storm or higher to hit the United States was Wilma in October 2005. It made landfall with 120 mile-per-hour winds in southwest Florida, killing five people as it pushed through the Everglades and into the Fort Lauderdale and Palm Beach area. It caused an estimated $21 billion in damage and left thousands of residents without power for more than a week. It concluded a two-year span when a record eight hurricanes hit the state.

In South Carolina, Governor Nikki Haley reversed the lanes of Interstate 26 so that all lanes of traffic were headed west and out of Charleston.

It was the first time the lanes had been reversed. Plans to reverse the lanes were put in place after hours-long traffic jams during Hurricane Floyd in 1999.

The governor planned to call for more evacuations on Thursday, which would bring the total to about 500,000 people in the state. Florida urged or ordered about 1.5 million to leave the coast, said Jackie Schutz, spokeswoman for Governor Rick Scott. Georgia had ordered around 50,000 people to evacuate.