For seven years — through political fights, Europe debt crises and market panic — investors could count on one thing: Short-term U.S. interest rates would stay locked near zero.

Such was the will of the Federal Reserve, which remained wary of the economy's durability long after the gravest recession since the 1930s had ended.

Now, with a vastly strengthened economy, the Fed is weighing whether to start phasing out the era of easy money on Thursday. It would be its first rate hike since 2006. Awaiting the decision, markets have been gripped by tension.

Ask some economists, and they'll tell you now is the time for a hike. Not so soon, others say.... Read More: ABC News