Here is only a partial list of America’s most important power centers this week: The St. Peter Lutheran Church in Greene, Iowa. The tiny airport in Atlantic, Iowa. The Boyd Building in Shell Rock, Iowa. The community center in Lidderdale, Iowa. The fire station in Prairiesburg, Iowa. The meeting room of the Moose Lodge in Cedar Rapids, Iowa. The Knights of Columbus Hall in Marion, Iowa. And the Masonic Lodge in Columbus City, Iowa.

This week, it begins. For months, candidates have canvassed and campaigned; tonight, Republicans will gather in caucuses in Iowa’s 1,784 precincts to begin a process that will lead to the GOP national convention in Tampa, Fla., Aug. 27, and to the presidential election on Nov. 6. The campaign began unusually late and came into focus with unusual clarity late in the year. Now its contours, but not its conclusion, are clear.

For the next 10 months, Americans will be preoccupied with their presidential choice, but the nature of that choice will be shaped by what happens in the next 10 days. Here is a viewer’s guide for the first vital weeks of Campaign 2012, beginning with a procedural question:

• How does what’s happening today in Iowa differ from what will happen next week in New Hampshire?

Iowa’s Republicans will begin the work of selecting convention delegates in evening caucuses rather than in the more conventional daylong primaries like the one in the Granite State. About 125,000 Republicans will travel in the Iowa cold to places like the American Legion Hall and the Masonic Lodge to take their stand and make their mark.

Surrounded by neighbors and family members, these Iowa Republicans often have to declare their choices publicly by clustering with, for example, the Newt Gingrich supporters in one corner of the room or with the Michele Bachmann supporters in another. This is democracy, prairie-style, but it is not a secret ballot; caucusers generally are subject to the sort of peer pressure that voters in New Hampshire’s primary will avoid.

One other important distinction: Only Republicans can participate in Iowa. Independents are free to join in the voting in New Hampshire.

• Will the Gingrich bubble be sustained?

The rise of the former House speaker, the subject of a House leadership coup that almost succeeded and a House reprimand that did succeed (by a 395-28 vote in a chamber controlled by his own party), is one of the most remarkable phenomena in political history. Left for dead politically at least three times, Gingrich enters the Iowa caucuses with unlikely but, in some mid-December polls, unambiguous strength.

A victory in the Iowa caucuses, which would seem less likely now than it did a fortnight ago, would transform the Georgian’s ascent from a political fluke to a political force, changing the dynamics of the political year. This is the principal question that will be determined by Iowa Republicans, who only four months ago delivered a startling (but meaningless) straw-poll victory to Bachmann.

• Will Mitt Romney’s performance in the 2012 caucuses differ from that of the 2008 caucuses?

Romney won the 2007 straw poll with a formidable display of financial muscle, but he finished second to former Gov. Mike Huckabee of Arkansas in the actual caucuses. He got 25 percent of the votes, which is within range of how he is polling this time around as his late push in the state aims to stanch the flow of support to Gingrich and blunt the rise of Rep. Ron Paul of Texas. Political professionals are not expecting Romney to prevail in Iowa. If he does, that would be a signal of political power that could clear the way to his nomination.

• How will Ron Paul do?

This is a question almost no one expected to be asking this month, but it could be one of the most important political indicators of the season.

The 2012 campaign is Dr. Paul’s third, and as Christmas approached, some polls showed him leading in Iowa, with a number of them showing him in third place nationally. The mainstream media have discounted Paul’s campaign. But of all the contenders, he has the most loyal cadre of supporters and the most consistent policy positions.

Paul also may have the most staying power. This is not insignificant. Nobody thinks he will win in 2012, just as nobody thought the Rev. Jesse Jackson would prevail in 1988. But Jackson’s reluctance to leave the race boxed in Gov. Michael Dukakis of Massachusetts politically and strategically. Paul could have the same effect on the 2012 Republican nominee, and though he has indicated he will not mount an independent campaign for president, a strong showing in Iowa could change his mind.

• What about the social conservatives?

These are the Iowans who changed the character of the Republican Party in the state, who made abortion one of the touchstones of Iowa politics, and who catapulted the Rev. Pat Robertson into a second-place finish in 1988, six percentage points ahead of Vice President George H.W. Bush, the eventual nominee.

Each political cycle, the presence of a large number of religious conservatives draws candidates like Huckabee, Bachmann and former Sen. Rick Santorum of Pennsylvania, who seems to be enjoying a bit of a late but perhaps well-timed boom, to the presidential race. Indeed, Iowa may produce two “winners”: the mathematical victor and the highest-ranking social-conservative candidate. The social-conservative candidate who finishes highest will have reason to continue in the race while others withdraw.

• Can the Iowa winner translate that into a New Hampshire victory?

It doesn’t happen every time. Indeed, not once since 1980 has the Republican victor in contested Iowa caucuses also captured the New Hampshire primary. Since 1980, only two Republican winners of contested Iowa caucuses (Sen. Bob Dole in 1996 and Gov. George W. Bush in 2000) have won the GOP nomination, while three winners of contested New Hampshire primaries (former Gov. Ronald Reagan in 1980, Vice President Bush in 1988 and Sen. John McCain in 2008) won the nomination.

That leads us to the conclusion that Iowa and New Hampshire will be the beginning of the campaign and not the end. The two contests bear watching, to be sure. But they only tell us who will persist in the race, not who will prevail.

David M. Shribman is executive editor of the Pittsburgh Post-Gazette. His email address is dshribman@post-gazette.com.