In President Bush's State of the Union address Tuesday night, odds are he will make reference to insurgents, perhaps more than once.

President Bush, though, would be only the latest U.S. chief to give the word major airtime. In his 1861 State of the Union, President Lincoln decried "insurgents in open rebellion to loyal citizens who are even now making great sacrifices," a line that could be borrowed for tomorrow night's address.

Plenty more interesting observations can be made by following the evolution of major presidential speeches, and you don't need to be a history buff to come up with your own.

Chirag Mehta, a 26-year-old IT manager from St. Petersburg, Fla., created a tool that breaks down most major presidential speeches -- State of the Union speeches, inaugural addresses and war declarations, among them -- going all the way back to the birth of the nation. His Web-based application, buried in his blog at Chir.ag, filters most of the major orations (accumulated online at sites like Encyclopaedia Britannica) for their 100 most frequently used terms.

Pull a slider from left to right and presidential history marches forward, yielding the top 100 most-used words in each oration.

These words are displayed in "tag clouds," an indexing method commonly used on blogs and other second-generation Web sites. Tag clouds -- weighted lists of keywords displayed in alphabetical order -- allow readers to visually sort information at glance.

For Mr. Mehta's "U.S. Presidential Speeches Tag Cloud," the size of a word depends on how frequently it is used in each individual speech; a larger font means heavy usage. Color varies to show how long a particular term has been in use: brighter colors indicate newer words in presidential lexicon, while well-worn words are given drab color and words in constant use are beige.

The system counts most variants, like terrorist and terrorism, as a single term. It's no surprise, when looking at recent speeches by President Bush, to see that "Iraq" is big and bright. In his most recent speech, calling for additional troops, the words "Anbar" and "Shia" make their tag cloud debut in a pure white font.

Vivid White Buzzwords

"One of the biggest trends I've noticed is that presidents have gone away from concrete action words and now focus on abstract feelings," Mr. Mehta says. "By the time you get to Nixon and LBJ, they're talking about 'commitment' all the time."

As years roll by, the word "war" becomes beige and never goes away, since it appears in every speech Mr. Mehta has catalogued. There are just two speeches where "war" isn't one of the top 100 most-used terms: George Washington's inaugural address in 1789 and FDR's 1935 speech on social security. Of course, a president needs to use a word more than once in a speech for it to crack his top 100 list and be compared with past orations.

Color coding signals major watersheds in American history. Slide over to 1812 and the words "war" and "British" leap out in a massive, brilliant white. In 1958, President Eisenhower turns "ballistic" and "missiles" into vividly white buzzwords, some seven years after President Truman did the same to "communism."

Color coding also makes plain President Bush's use of the word "terrorism." The word appears in shocking white within the tag cloud for Mr. Bush's Sept. 20, 2001, speech declaring war on terrorism -- and it remains roughly the same dominant size in every subsequent tag cloud for the next five years.

A casual survey of Mr. Mehta's presidential "tagline," as he calls it, generates all sorts of insights. "Intercourse" is one of Mr. Mehta's favorite examples. "I don't think Bush is going use that word in his State of the Union speech," he predicts, "but that was a pretty common word in the early speech history."

In December 1825, President Adams, while describing the relationship between the U.S. and Europe, says, "During the same period our intercourse with all those nations has been pacific and friendly; it so continues."

"Vessel" is another early fixture of presidential vocabulary that has been left to languish by modern administrations. In Thomas Jefferson's 1802 State of the Union address, "vessel" is clearly the single most dominant term. Mr. Jefferson complained, for example, that European trade policies "tend effectually to prohibit the carrying thither our own produce in our own vessels."

"Constitution" emerges a presidential obsession in the early 19th century but vanishes almost entirely by the 20th century. "Family" goes from big to huge as the tag clouds from the Reagan '80s to the Clinton '90s.

'Cliff Notes Project'

As the creator makes clear, he's no amateur historian: "I don't know much about U.S. history," he admits. "This was more of a Cliff Notes project for me." He first drew up the tag-cloud software as a way to index his personal blog.

When he began blogging five years ago, online tagging as we know it didn't exist. So rather than re-read his old posts and add keyword tags, Mr. Mehta wrote a program that sifts through his archives to filter out his frequently used words by the month.

"I learned that around 2004, when I moved to Florida, the word 'hurricane' became important in my life," he says. Then he decided to apply the software to "something that would actually be interesting to people."

He launched his presidential-speech-tag could shortly before the November elections, and the page attracted more than a million hits in the first two weeks, he says. Now, Mr. Mehta reports, between 500 and 1,000 visitors access the page each day. The tag-cloud software is available free, distributed through a Creative Commons license on Mr. Mehta's site.

The process is easy, he says: Just copy the text and plug it into his "tagline" generator, which strips out common words like "the" or "and," combines similar words like "Iraq" with "Iraqi," and reveals the most-used terms in cloud form. The software will then compare the newest speech to all the earlier ones in his collection, determining which words are new additions and which are old standbys and assigning font colors to each.

Mr. Mehta is applying the software elsewhere. Last month, Seattle Post-Intelligencer reporter Todd Bishop asked Mr. Mehta for help applying the same tag-cloud technique to Microsoft's history. The result digests three decades of key speeches, interviews and internal emails.

And he isn't planning to abandon his presidential archive. Mr. Mehta expects to have a tag cloud up for Tuesday night's State of the Union address 10 minutes after the White House posts the speech online.