The Vermont senator's candidacy exceeded expectations by virtually every measure -- raising more money, winning more delegates and generating more excitement than even his most optimistic allies initially believed possible.
Here are nine high-flying moments Sanders and his loyal "Berniecrats" will be sure to remember as they take their cause to the Democratic convention in Philadelphia, where Clinton will be nominated.
Trailing by double-digits in late tracking polls, the upset victory breathed new life into a contest Clinton was hoping to wrap up early.
"What tonight means is that the Bernie Sanders campaign, the people's revolution that we're talking about, the political revolution that we're talking about, is strong in every part of the country," Sanders told reporters afterward. "And, frankly, we believe our strongest areas are yet to happen."
For Clinton, who already had her eye on the general election, it was a wakeup call.
A day before the vote, she told supporters that "the sooner I could become your nominee, the more I could begin to turn my attention to the Republicans."
But the Michigan result ratified Sanders' appeal to blue-collar Democrats and gave the candidate and his staff a reason to dream big.
2. Spring awakening
The high hopes lasted about a week. Clinton swept all five March 15 contests, again pushing Sanders to the brink.
But again, the Vermont senator's campaign rallied. He went on to win six of the next seven contests, including a 13-point victory in Wisconsin on April 5.
The Badger State had been kind to Sanders since the early days of the campaign and his arrival felt like a sort of homecoming. In Janesville, he told supporters
he considered the state's embattled labor unions "family" and promised to use his presidency to "rebuild the trade union movement in this country."
3. Meet 'Birdie Sanders'
It was the bird landing that launched a million memes. At a rally in Portland, Oregon -- because, of course
-- the friendly feathered creature decided to get an up-close look at the candidate. Sanders paused his speech, first in shock and then delight, before offering a broad grin and welcome to the uninvited guest.
"I think there may be some symbolism here," Sanders said. "I know it doesn't look like it, but that bird is really a dove asking us for world peace."
The rest is illustrated history, as his supporters celebrated the serendipitous visit on signs, T-shirts and across the Internet. By night's end, "Birdie Sanders" was a campaign legend.
4. Flexing fundraising might, $27 at a time
On Sept. 30, 2015, months before the first votes were cast, the Sanders campaign announced
that it had received its 1 millionth online donation.
The Vermont senator's small-dollar fundraising machine -- fueled by those $27 average contributions Sanders so frequently touted -- kept the upstart campaign burning long and strong, all the way to the final contest, in Washington, D.C., on June 14.
He pulled in nearly $3 million after a narrow loss in Iowa and by April had equaled Clinton's haul
. The courtship of Sanders' dedicated donor base will be a priority for the Clinton as the general election campaign hurtles toward November.
5. Packing the house
Big crowds might not win elections, but they generate headlines, can scare rivals, and give a small campaign like Sanders' a unique opportunity to gather information and build up its email list.
This candidate's talent for turning out supporters by the tens of thousands came into focus during a West Coast swing in August 2015. On a Sunday night in Portland, Oregon, more than 19,000
people filled a basketball arena to hear him speak. Arena officials said an additional 9,000 showed up but were unable to get inside. The Washington Post estimated that, over the course of a few mid-summer weeks, more than 100,000
attended his rallies.
Along with the crowds, the belief that Sanders could mount a real challenge was growing. Would-be Sanders backers took notice -- and you can bet Clinton's supporters did, too.
6. A lovefest in Burlington
After making a low-key formal entry into the race, first with an email and then at a small press conference outside the U.S. Capitol, Sanders on May 26, 2015, returned to Vermont to kick off his "political revolution" at a homecoming-style rally on Lake Champlain in Burlington.
Surrounded by friends -- including "Ben and Jerry," whose free ice cream melted in the afternoon heat -- and thousands of supporters in the city he served as mayor from 1981 to 1989, Sanders pledged "to build a movement of millions of Americans who are prepared to stand up and fight back."
7. 'Live' with Larry David
If there were any doubt that Sanders had emerged as a political force, it was dispelled the moment Larry David debuted his pretty, pretty good impression of the senator in an October 2015 episode of "Saturday Night Live." But it was Sanders' own appearance, as "Bernie Sanderswitsky," in a skit alongside David on February 6 that cemented his mainstream celebrity.
"I am so sick of the 1% getting this preferential treatment," Sanders cried, in character and on point, as rich passengers boarded lifeboats on a sinking Titanic. "Enough is enough! We need to unite and work together if we're all going to get through this."
David also starred as a cranky hybrid of himself and Sanders in a standout sketch
called, "Bern Your Enthusiasm," a nod to the comedian's popular HBO show.
8. Victory in the Granite State -- and a milestone
After a narrow loss to Clinton in Iowa eight days earlier, Sanders won the New Hampshire primary by more than 22 points. The victory, his first in 2016, was also the first by a Jewish candidate in a presidential nominating contest, although Sanders wasn't one to play up that fact.
"Tonight, we have sent a message that will echo from Wall Street to Washington, from Maine to California," he told delighted supporters, before getting in a jab at the Clinton campaign.
"They are throwing everything at me except the kitchen sink," Sanders roared, "and I have the feeling that the kitchen sink is coming pretty soon as well."
Indeed it was -- but over the next four months, the unlikely candidate gave as good as he got, and in the process, established himself as a hero to his loyal backers and a leading figure in the American progressive movement.
9. 'Rome is berning'
Was it great timing? Perhaps not. Sanders flew to the Vatican on a Friday to address a conference on social, economic and environmental issues -- less than a week before the crucial New York primary.
He would lose the Empire State, but did enjoy a brief audience with Pope Francis.
What did Sanders say?
"I just wanted to let him know," Sanders told CNN
, "how appreciative I was and the extraordinary role he's playing throughout the world in raising consciousness about massive levels of income and wealth inequality."