As voters and analysts cast an eye forward to the presidential race a year out, two words of caution should serve as a reminder: Things change.
A year is several lifetimes in politics, but it is also a lot of time for the landscape around an election to be altered, sometimes in dramatic ways.
Consider the 2008 election, which at the outset was supposed to be a referendum on the wars in Iraq and Afghanistan — until the focus turned sharply to the tumbling economy.
Look at the last two presidential elections and you'll see evidence for how much things can change in 12 months time in the nation's employment picture, presidential approval and the stock market.
The Unemployment Rate
Underlying all presidential elections is a basic question: Are you better off than you were four years ago? In many ways the unemployment rate is the most direct way to answer that question. It hits deep at the American psyche. And here's the thing, it moves quite a bit.
That's actually quite a bit of change in that table, even in the 2012 election cycle. The current rate is 5.1 percent, the lowest it's been since early 2008. That's good news for the Democratic nominee (who will represent continuity) for now, but it was good news for Republicans too - in November 2007, before everything changed.
Elections are ultimately about how voters feel about the current occupant of the White House (and his party). And, as the last few elections show, those feelings can change quite a bit in that last year before the vote.
George W. Bush's dismal 31 percent approval number in 2007 was probably not going to get a lot better in a year (though the drop didn't help the Republicans). But look at Barack Obama's 44 percent in 2007. That's a pretty marginal number. A year later, he had climbed to 49 percent approval and he won reelection.
Mr. Obama's job approval number currently sits at 47 percent. Where it sits next October or November will offer a strong hint about the choice voters may make on Election Day.
The Stock Market
Among the most volatile day-to-day figures in the American political-economic conscious are the stock indices. The winning and losing streaks of the Dow Jones Industrial Average and its inevitable peaks and valleys are in the headlines on the tickers rolling along the bottom of the news channels.
Only about half of all Americans have money invested in some stock market - through individual stocks, mutual funds or I.R.A. accounts - but, for better or worse, the number has come to be seen as a barometer of the nation's larger economic health.
The correlation here is pretty obvious. In 2008, the Democratic nominee (Mr. Obama) won the White House as the economy was tanking. And he held it in 2012 through the sluggish recovery that saw the Dow experience good growth in the year before the election.
With Americans lukewarm on the economy, this will be one of the key numbers to watch as "things change" over the next year. The 2015 calendar year has been a volatile one for Wall Street. In August the Dow was more than 2,100 points below its January starting point. It's since recovered almost all of that and sits essentially flat.
Of all the numbers here the DJIA may be the most likely to move dramatically in the next 12 months and if it does, the direction it moves could heavily impact the issues and environment that drive the discussion next fall.