This weekend's massive flash rallies to protest President Trump's immigration policies — following the global women's marches and the March For Our Lives after the Parkland school shooting — represent a unified, accelerated activism surpassing even what was seen in the late '60s, social movement historians tell me.

The speed and scale of yesterday's pop-up protests is fascinating:

• "Protesters flood U.S. cities," AP writes in its roundup: "In major cities and tiny towns, hundreds of thousands of marchers gathered Saturday across America, moved by accounts of children separated from their parents at the U.S.-Mexico border, in the latest act of mass resistance against President Donald Trump’s immigration policies."
• "Protesters flooded more than 700 marches, from immigrant-friendly cities like New York and Los Angeles to conservative Appalachia and Wyoming."
• "They gathered on the front lawn of a Border Patrol station in McAllen, Texas, near a detention center where migrant children were being held in cages, and on a street corner near Trump’s golf resort at Bedminster, New Jersey, where the president is spending the weekend."

Experts in social movements say that what we're seeing is totally new — befitting, and powered by, our times and our technology.

Peter Dreier — who teaches politics and chairs the Urban & Environmental Policy department at Occidental College in Los Angeles — said the current movements unite the left's strands in a way we haven't seen in nearly a century:

• During the Great Depression of the 1930s, people could see the system wasn't working, and so you saw similar protests by farmers, workers, consumers and college students.
• But during the late 1960s, protests were very factionalized: Unions, women, environmentalists and civil rights advocates often worked in their own lanes.
• Ever since, there's been a big inside-outside split on the left between electoral politics and protest politics.
• Now, Dreier says: "The best thing Donald Trump has done has been to revive massive protest in America."

Elaine Weiss, author of "The Woman's Hour: The Great Fight to Win the Vote," told me that what's "different about the waves of demonstrations of the past 18 months is their spontaneity — made possible by new technology and mastery of social media."

• "Suffrage marches took months to plan and organize in the early 20th century — by mail and phone; participation depended upon personal contact and connection, with printed announcements laboriously tacked to walls. They usually occurred in one city at a time."
• "The Woman's March of January 2017 was organized within a matter of weeks — thanks to social media — with demonstrations taking place around the country and across the globe."
• "The Never Again [gun control] rallies were arranged in an even shorter time — the younger the constituency, the more adept the social media organizing."
• "And this weekend's immigration policy protests came together within a matter of days, and took place in almost every community in America. Power to the hashtag!"

Be smart, from Weiss: "Our current zeitgeist of frustration and rage is the perfect ecology for these Instagram-ready demonstrations."

P.S. Asked for comment on yesterday's demonstrations, Department of Homeland Security press secretary Tyler Houlton said:

• “We appreciate that these individuals have expressed an interest in and concern with the critical issue of securing our nation’s borders and enforcing our immigration laws. As we have indicated before, the Department is disappointed and frustrated by our nation’s disastrous immigration laws and supports action.  Only Congress can ensure that our border is secured and families are protected. We thank them for their interest.”

"The turmoil on the left mirrors that of Republicans in the first two years of Mr. Obama’s administration, when Democrats controlled all the levers of government and left the Tea Party-inflected Republican Party to thrash around in impotent protest, raging with an energy that eventually propelled it back to power," the N.Y. Times' Jonathan Martin and Alex Burns write:

• "But some Democrats see the moment in even more sweeping terms, akin to the era following the Vietnam War and Watergate, when the reaction to a controversial Republican president triggered a moderate and liberal backlash. That movement delivered dozens of new seats, but it also unleashed a generational changing of the guard that jolted party leaders."

Be smart: "What worries some Democratic elders ... is that activists will harbor unrealistic expectations of what sort of policies newly elected progressive lawmakers can push through in a still-divided capital."

• John Lawrence, former chief of staff to Nancy Pelosi and author of a book on the Watergate Babies, "The Class of '74": The activists "say to new members, ‘You won because of us.' Actually no, typically you win because you were able to win moderate voters disgusted with incumbents.”
• "There is also a group of younger Democrats uneasy about the party drifting too far left.

P.S. ... N.Y. Times: "A page featuring results from New York's primary elections was the week's most popular article. More than half of readers checked results from their phones, and over 40 percent found the article via search engine."

Jeffrey Toobin in the forthcoming issue of The New Yorker, "How Trump’s Supreme Court Pick Could Undo [Justice Anthony] Kennedy’s Legacy ... What rulings would a brazen conservative majority produce?"

• "The whole purpose of Trump’s Supreme Court selection process has been to eliminate the possibility of nominating someone who might commit Kennedy’s perfidies of moderation."
• "Yet it’s far from certain that the public wants the kinds of rulings that a brazen conservative majority would produce. So the nominee and his or her supporters will avoid spelling out the implications of this judicial philosophy."
• "As with [Justice Neil] Gorsuch, the nominee will be supported with meaningless buzz phrases: he or she will be opposed to 'legislating from the bench' and in favor of 'judicial restraint.'"

"It’s all the more important, then, to articulate in plain English what, if such a nominee is confirmed, a new majority will do":

• "It will overrule Roe v. Wade, allowing states to ban abortions and to criminally prosecute any physicians and nurses who perform them."
• "It will allow shopkeepers, restaurateurs, and hotel owners to refuse service to gay customers on religious grounds. It will guarantee that fewer African-American and Latino students attend élite universities. It will approve laws designed to hinder voting rights. It will sanction execution by grotesque means. It will invoke the Second Amendment to prohibit states from engaging in gun control, including the regulation of machine guns and bump stocks."

Be smart: "In many respects, the most important right-wing agenda item for the judiciary is the undermining of the regulatory state."

• Worthy of your time.

Another view ... Adam J. White, a research fellow at the Hoover Institution and director of the Center for the Study of the Administrative State at George Mason University’s Antonin Scalia Law School, for The Weekly Standard:

• "No matter what activists are shouting, Roe and Obergefell [same-sex marriage] are not in imminent danger of being 'overturned.'"
• "But Roe and Obergefell are now unlikely to enjoy the persistent expansions that many progressives hoped the Court would be undertaken over the next two decades."
• "Justice Kennedy’s retirement happens to occur in the most poisonous political year of the last half-century. Which means that we are about to face a political and cultural storm of the century."

Sunday best ... Sen. Susan Collins (R-Maine), to ABC's Martha Raddatz on "This Week," about her conversation with President Trump:

• "I told him that I was looking for a nominee that would demonstrate a respect for precedence. ... I mentioned judicial temperament, integrity, intellect, experience, qualifications, fidelity to the rule of law and the constitution. But most important of all, a respect for precedence."

"Since his inauguration, the president has tweeted about Fox News or Fox Business more than 220 times," Michael Grynbaum writes in a N.Y. Times front-pager, "Fox and Trump: It’s a Friendship Without Equal."

Backstory: "In 2011, Fox News announced that [Trump] would appear weekly on 'Fox & Friends' ... [A]t a meeting with senior producers, ... [Roger Ailes] said Mr. Trump appealed to Fox News viewers because he lived his life in a manner that many of them imagined they would, too — if they were rich."

• "Trump was a white male in his 60s, squarely in the network’s core audience, and his unfussy patriotism and keen sense of aggrievement made him a natural fit for the Fox News aesthetic."

"The Seattle region is home to America's two richest men, but their local legacies to date represent two very different eras for the city," AP's Sally Ho writes:

• "While Amazon's Jeff Bezos is blamed by some for rising rents and clogged city streets, Bill Gates is largely admired for helping lead the computing revolution and donating billions through his philanthropy."
• "The Microsoft co-founder's legacy here includes opening the world's largest private charity across the street from the Space Needle, creating housing for homeless families and supporting charter schools."
• "Microsoft was the first tech company to dramatically change the region's economy as it grew quickly in the 1980s and 1990s."
• "Today, Seattle is booming again with housing prices skyrocketing thanks to online retail giant Amazon's explosive growth that has added tens of thousands of well-paid workers to the area."

"Gates has largely escaped the criticism directed at Bezos and other tech leaders as Seattle loudly debates how to respond to the advantages and downsides of being the United States' fastest-growing big city":

• "[T]hanks to the billions he now gives away each year, Gates has managed to shed his reputation as a laser-focused, sharp-elbowed tech billionaire."

Steal some time with Bloomberg Businessweek's "Heist Issue":

• "Did This Jeweler to the Stars Commit the Biggest Bank Fraud in India’s History?" by Samanth Subramanian: "Nirav Modi didn’t seem like the kind of person who needed to rob $2 billion from a bank." I'm hooked!
• "How to Steal 50 Million Bees," by Josh Dean: "Every winter, apiarists from all over America rent their hives to farmers in California, attracting the attention of some very specialized thieves." You got me!
• "IfYou Steal It, the Art Vigilante Will Find You," by Vernon Silver: "Using a secret database of tens of thousands of photos, Christos Tsirogiannis is fighting to prevent auction houses from selling looted art." I'm in!
• "The Biggest Digital Heist in History Isn’t Over Yet," by Charlie Devereux, Franz Wild and Edward Robinson: "Carbanak’s suspected ringleader is under arrest, but $1.2 billion remains missing, and his malware attacks live on. ... Since late 2013, this band of cybercriminals has penetrated the digital inner sanctums of more than 100 banks in 40 nations, including Germany, Russia, Ukraine, and the U.S., and stolen about $1.2 billion." Go on!