After a weekend growth spurt, the New York financial district sit-in “Occupy Wall Street” has blossomed into not only a national movement, but also a global one.

More than 100 cities have clocked in under the “Occupy” moniker, with more names appearing on the movement’s unofficial cyber bulletin board, occupytogether.org, every few digital minutes.

Large and small towns as well as regions and states are onboard, from Mobile, Ala., to Merced, Calif., to Adelaide (Australia), Cork (Ireland), and Cologne (Germany). The swiftly expanding, loosely organized, and casually affiliated network of protesters is taking over public spaces with sleeping bags, sandwiches, and placards.

These groups are armed with everything from manifestoes ­– their essential grievance is that financial institutions have too much political influence, to the detriment of almost everyone else – to a circulating library staffed with an actual librarian, trash disposal teams, and advice on how to properly safety-pin a dollar bill.

The protesters are predominantly under 30; are communicating via Twitter, Reddit, Facebook, and even e-mail; and are sharing grievances, doling advice to newcomers, and self-consciously declining to set out a formal list of demands. They are also showing signs of preparing for a protracted battle.

According to the Occupy website, the movement has emerged from a climate of outrage over perceived economic injustices and is taking inspiration from recent social protests in the Middle East.

“Occupy Wall Street is a leaderless resistance movement with people of many colors, genders and political persuasions,” reads a statement on the website. “The one thing we all have in common is that we are the 99 percent that will no longer tolerate the greed and corruption of the 1 percent,” the statement says. “We are using the revolutionary Arab Spring tactic to achieve our ends and encourage the use of nonviolence to maximize the safety of all participants.”

As the movement spreads, political analysts and social scientists are asking whether this is the sort of social unrest that emerges only in hard economic times and recedes in better days, or is a sign of a new political movement emerging on the American landscape.

While it may be too early to say for certain, David Johnson, an Atlanta-based Republican political strategist, suggests the former.

“It’s drawing in everyone across the political spectrum,” he notes, pointing to the range of voices being heard in the media coverage. “They have everyone from libertarians, to liberals, moderates, socialists, and hard-line conservatives,” he says, adding that this sort of coalition works well for a short period of protest.

“This kind of fractious group won’t hold together for the long run," says Mr. Johnson. "They can do a short protest, but they’re much too disparate to be the beginnings of a long-term movement.”

Irrespective of the group’s fellow travelers, the movement’s origins give a clearer sense of its orientation, direction, and potential for long-term impact, says Villanova University Prof. Matthew Kerbel. Unlike the tea party, which is rooted in the political right, Occupy Wall Street has its roots on the political left, says Professor Kerbel, author of “Netroots: Online Progressives and the Transformation of American Politics.”

The movement was sparked by individuals targeting what they see as the excessive political pull of big banks and the financial sector in contributing to policies they feel are detrimental to the middle class, says Professor Kerbel, a message that echoes “the argument made for several years now by online progressive organizations and blogs.”

“Its organizers have taken advantage of social media and progressive blogs to spread their message, especially when it appeared that the mainstream press wasn’t paying attention,” he says via e-mail.

The movement has also attracted the attention and support of more traditional liberal organizations, such as organized labor, he notes. This group includes the United Federation of Teachers and the Transport Workers Union, some of whose members defied a New York City police request and refused to bus protesters arrested Saturday for blocking traffic on the Brooklyn Bridge.

The movement shows signs of readying for the long haul, says Heather Gautney, a professor of sociology at Fordham University in New York.

“In the spirit of the globalization movement, this is a ‘leaderless movement,’ ” she says via e-mail. Occupy Wall Street is now a “movement of movements.”

The groups involved do not seek to replicate the nondemocratic, hierarchical structures of the organizations they oppose, she notes, in part because having a leadership can be dangerous. The police can easily target leaders, and if the movement’s health depends on them, notes Professor Gautney, “it can fall apart more quickly.”

Americans should be prepared to see this movement take hold and spread, says MIT economics professor and lawyer Nicholas Ashford, author of “Technology, Globalization, and Sustainable Development – Transforming the Industrial State: Exploring the Critical Conflicts between Economy, Environment, and Employment.”

It’s not just a matter of people being “mad as hell and not taking it anymore,” he says. “It’s more crucially the dawning realization that the US economy was always built on quicksand, and that our current dismal state is not the anomaly, but the reality.”

“Instead of waiting for the economy to ‘bounce back’ to a previous state of health that was nothing but a sad illusion,” says Professor Ashford, “Washington, Wall Street, and big business need to address a strategy for moving forward from where we are,” not from where they thought we were.