Amazon’s growth has had an outsize effect on the local office market, helping to drive down vacancy rates and resuscitate the investment climate. The office vacancy rate in the fourth quarter dropped to 12.4 percent from 13.6 percent at the end of 2010, according to Kidder Mathews, a commercial brokerage in Seattle. By the end of this year, the vacancy rate is projected to fall into the single digits.

“You certainly can’t argue that Amazon by far and away has been the big driver,” said Chris Moe, a senior vice president at Kidder Mathews. “But it’s not all Amazon. It’s them and two dozen other healthy local companies.”

As vacant space leaves the market, downtown landlords are feeling more confident and leasing prices are starting to creep up. Buildings that broke ground before the recession and were completed at the depth of the market three years ago are starting to fill. Net absorption, or the amount of space companies rented and occupied, grew to 1.9 million square feet last year, Kidder Mathews said, the most in the last five years.

Schnitzer West, a Seattle developer, brought two office towers to market after the real estate collapse and struggled to find tenants. Real estate brokers wondered if Schnitzer, normally seen as savvy, had completely mistimed the market. But early last year, Amazon agreed to move in, taking over more than 22 floors of the 36 stories at one of the towers, 1918 Eighth Avenue. The lease for 460,000 square feet was the biggest for the area since before the economic downturn.

“Nineteen eighteen was our poster child of what not to do,” said Dan Ivanoff, the founder of Schnitzer West and the company’s managing investment partner. “It was a tough slog, but we were fortunate that Amazon leased it. We want to mitigate risk very well, we don’t want to be lucky.”