President Obama signed the $787 billion economic stimulus package into law on Tuesday, setting in motion a wave of spending and tax cuts intended to lift the country out of a 14-month recession.
The plan aims to create or save about 3.5 million jobs, many of them in infrastructure and renewable energy projects.
Obama said the measure marked "the beginning of the first steps to set our economy on a firmer foundation."
He said the plan will put Americans to work in jobs that will build the foundation for growth in the future, and that the plan is one phase of a broader plan to put the economy back on track.
The White House launched a Web site, www.recovery.gov, to allow the public to track how the stimulus money is spent.
Obama signed the measure at the Denver Museum of Nature & Science, a century-old building that recently had 465 solar panels installed on the roof. The site was selected to highlight the provisions in the stimulus package that aid the growth of the renewable energy industry.
The measure also includes a $400 tax break for most individual workers and $800 for couples. It gives aid to states, provides financial incentives to buy homes and cars, increases unemployment benefits and food stamps, and subsidizes health insurance for laid-off workers and the poor.
The president faced a supportive crowd at the museum, but conservatives planned to protest the measure on the steps of the state capitol.
I don't want to pretend this marks the end of our economic problem, nor does it represent all we are going to have to do," the president said. But Obama said the most sweeping economic recovery package in U.S. history would put the country back on track for economic growth.
Obama was scheduled to unveil yet another part of his economic recovery effort Wednesday in Arizona: a plan to help millions of homeowners avoid foreclosure. Phoenix has one of the highest foreclosure rates in the country.