They may exist in the shadows, but the estimated 1.4 million undocumented workers in Texas are helping build up the economy.

"There is economic benefit from these undocumented immigrants," said Carole Keeton Strayhorn, Texas comptroller.

A report released Thursday by the Comptroller's office shows illegal immigrants pumped nearly $18 billion in 2005.

"At the state level, it shows the positive impact," Strayhorn said.

But at the local level, counties across Texas pay a price when it comes to healthcare and law enforcement services.

"You leave local governments in a hole," Strayhorn said.

The cost of illegal immigrants to the Williamson County Sheriff's Office was nearly $495,000, according to the report. In Travis County, the cost to law enforcement was $4.7 million.

"It's a cost for food, for security, for clothing [of inmates]," said Roger Wade, spokesman for the Travis County Sheriff's Office.

Overall, the state still sees an economic boon to the tune of nearly $18 billion. And that's something immigration activists like Ana Yanez-Correa have said for a long time.

"The contributions are tremendous," she said.

Now, the new numbers may fuel an ongoing immigration debate.

"In order for policy makers to make sound policy decisions, they need the facts," Yanez-Correa said.