WASHINGTON — U.S. banks are ending the year with their best profits since 2006 and fewer failures than at any time since the financial crisis struck in 2008. They’re helping support an economy slowed by high unemployment, flat pay, sluggish manufacturing and anxious consumers.

As the economy heals from the worst financial crisis since the Great Depression, more people and businesses are taking out — and repaying — loans.

And for the first time since 2009, banks’ earnings growth is being driven by higher revenue — a healthy trend. Banks had previously managed to boost earnings by putting aside less money for possible losses.

“We are definitely on the back end of this crisis," says Josh Siegel, chief executive of Stonecastle Partners, a firm that invests in banks.

The biggest boost for banks is the gradually strengthening economy. Employers added nearly 1.7 million jobs in the first 11 months of 2012. More people employed means more people and businesses can repay loans.

Small and midsize banks have taken longer to rebound. They held risky commercial real estate loans used to develop malls, industrial sites and apartment buildings. Many such loans weren’t repaid. But as the economy has strengthened, fewer such loans have soured, and many small and medium-size banks have recovered.

Many banks complain they’ve been hampered by new regulations, especially stricter requirements for the capital they must hold to protect against unexpected losses. Some of the biggest banks say their customers have held off on borrowing in part because of slower global growth and concern about the fiscal cliff.