WASHINGTON — A multibillion-dollar information-sharing program created in the aftermath of Sept. 11, 2001, has improperly collected information about Americans and produced little valuable intelligence on terrorism, a Senate report concludes.

What began as an attempt to put local, state, and federal officials in the same room analyzing the same intelligence has instead cost huge amounts of money for data-mining software, flat screen televisions, and, in Arizona, two fully equipped Chevrolet Tahoes now used for commuting, investigators found.

The bipartisan report is a scathing evaluation of what the Department of Homeland Security has held up as a crown jewel of its efforts. The report underscores a reality of post-Sept. 11 Washington: National security programs tend to grow, even when their money and staffing far surpass the actual danger presented by terrorism. Much of this money went for ordinary local crime-fighting.

Disagreeing with the critical conclusions of the report, Homeland Security said it is outdated and too focused on information produced by the program, ignoring benefits to local governments.

Because of a convoluted grants process set up by Congress, Homeland Security officials don’t know how much they have spent in their decade-long effort to set up so-called fusion centers in every state. Government estimates range from less than $300 million to $1.4 billion in federal money, plus much more invested by state and local governments. Federal funding is pegged at about 25 percent.

Congress is unlikely to pull the plug. That’s because, whether or not it stops terrorists, the program means politically important money for state and local governments.