James: Miami was "almost like college"

In the SI piece, James said he'd still have left for Miami if he had to do it all over again. It could be described as the college experience that he never had.

"Miami, for me, has been almost like college for other kids," James, who went pro straight out of high school, said in Sports Illustrated. "These past four years helped raise me into who I am."

His ties to his home, he said, pulled him back.

"My relationship with Northeast Ohio is bigger than basketball. I didn't realize that four years ago. I do now."

Bringing trophy to Cleveland "most important"

James' Instagram account Friday had a photo, showing him in a Cavaliers jersey, said: "I'm coming home."

In the SI piece, James wrote that his "goal is still to win as many titles as possible, no question."

"But what's most important for me is bringing one trophy back to Northeast Ohio," he wrote.

"I'm not promising a championship. I know how hard that is to deliver," James added. "We're not ready right now. No way. Of course, I want to win next year, but I'm realistic. It will be a long process, much longer than it was in 2010."

White House takes notice

The news generated intense interest as soon as it broke, around 12:30 p.m. ET Friday. Three of the top 10 trending terms on Twitter were almost instantly related to James.

It even came up in the daily press briefing at the White House. When asked, White House Press Secretary Josh Earnest said he didn't know if noted NBA fan President Obama had a reaction to James' move.

But Earnest added: "The fact that he has made this decision is a testament to the kinds of values that he has incorporated into his life and he says that he is interested in instilling in his children."

"I think it is a pretty powerful statement about the value of a place that you consider home," Earnest said.

Professional athletes weighed in. From Seattle Seahawks quarterback Russell Wilson on Twitter: "Congrats to my man @KingJames on Cleveland! Too bad we don't have the #Sonics #NoPlaceLikeHome."

Baltimore Ravens wide receiver Torrey Smith said on Twitter: "I'm happy Lebron is going to CLE....not that he owes anyone anything but he means more to that city than anywhere else in the world! Iconic."