American politics may be tumultuous, but not the economy, where the story in recent years has been consistent job growth, shrinking unemployment, and record stock market highs.

The question is: Can this continue through 2018?

Imminent threats are tough to spot, but there are gathering signs that our long recovery may be entering its final phase, including a warning light in the bond market and the Federal Reserve’s eagerness to hit the brakes.

Here are some things to watch for in the months ahead, as we try to sustain overall growth — and maybe even boost wages — while also staving off the recession that we can’t avoid forever.

Stimulative tax cuts, meet the stingy Federal Reserve

A power struggle lies ahead — a sort of economy-shaping staring contest between the Republicans’ tax plan and the Federal Reserve.

The tax bill is expected to provide its largest shot of stimulus right away, enough to raise gross domestic product growth from the currently anticipated 2.5 percent to nearly 3.3 percent, according to an estimate from the nonpartisan Tax Policy Center.

But only if the Fed allows it. And we really don’t know how the Fed plans to respond, because this sudden stimulus is a surprise. When the Fed last met, in December, the draft version of the Republican tax bill was targeted at 2019, not 2018.

So rather than the two to four rate hikes Fed members then projected, we may see a lot more — each an effort to slow an economy at risk of redlining as a result of tax-fueled growth. Collectively, those hikes could have an unpredictable impact on labor markets and overall growth.

Watch for popping bubbles

Recent US recessions have followed a bubble-and-bust pattern. In 2007, it was the housing market; in 2001, the dot-com era.

At the moment, there isn’t an obvious candidate for a systemwide bubble, but there is some frothiness. Take the stock market, which has been rising steadily for more than a year. Prices are now approaching levels that have historically signalled a coming correction, or sometimes something worse.

And then there’s bitcoin, everybody’s favorite example of the bubble that just won’t pop. Right now, a collapsing bitcoin probably wouldn’t have a big real-world impact. Late-to-the-party investors would lose big and a techno-utopian idea would crack, but most of us would be unharmed. However, every time a new investor or bank jumps on the bitcoin bandwagon, the risk spreads. And if bitcoin becomes an entrenched part of our financial system, its stability will be a national concern. (Disclosure: I owned a small amount of bitcoin, but sold it last month.)

Short-term vs. long-term

Recessions are notoriously hard to predict. But there is at least one frequently eyed canary in our economic coal mine, and it looks increasingly woozy.

It’s all about the relationship between short- and long-term government bonds. In normal times, long-term bonds are supposed to offer higher returns — the longer the government wants to hold on to your money, the more it has to pay you for the privilege.

That changes when investors see trouble ahead. Then, they want their money tied up in a stable long-term bond so it can hold its value as the economy crashes. The result is a worrying situation called an inverted yield curve, where long-term bonds become strangely chintzy, offering lower returns than short-term ones.

We’re not there yet. A 10-year Treasury bond still pays about 0.5 percentage points more per year than a 2-year Treasury bond. But 12 months ago those bonds were paying 1.25 percent more — meaning the gap has been shrinking quickly. Continued narrowing would be a bad sign for our economic future.

Beware the unknown unknowns

It’s easy to imagine scenarios where unexpected world events produce far-reaching tremors. Take, for example, the protests that have recently broken out in Iran. If Iranian protesters somehow topple the country’s regime — or spark a civil war — the price of oil could fluctuate wildly, upending business plans around the globe.

Or consider China, which has a massive overhang of government, corporate, and household debt. For years, prognosticators have been warning that this could set off an economic crisis not unlike the financial meltdown that brought down the US economy in 2007. So far, they’ve been wrong, but the risk remains real.

To a degree that we rarely acknowledge, America’s economic future hinges on factors we can’t reasonably foresee. Which is part of what makes it so hard to predict the economic future. In the end, 2018 could easily wind up being like 2017, another stable year in our long economic recovery. Or not. The challenges ahead are real, and the hourglass running thin. Already this is the third-longest expansion since World War II. If it survives past June 2019, it will be the longest.

Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the nation. He can be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz.