Two months after a deadly bridge collapse in Minnesota, state transportation officials nationwide continue to wrestle with how to preserve and upgrade thousands of bridges while short on money, officials said Sunday.

With an estimated 74,000 bridges in the country classified as "structurally deficient" — the mark given to the Interstate 35W bridge in Minneapolis — and with federal funding not a certainty, most transportation officials agree that the burden of devising safety strategies will fall to the states.

Transportation officials from across the country held a brainstorming session on the issue Sunday during a conference sponsored by the American Association of State Highway and Transportation officials. A number of states have already been working on the problem for decades, well before the August collapse, which killed 13 people, injured about 100 and thrust the safety of the nation's bridges into the spotlight.

One problem is that federal funding seems to reward poor stewardship — that is, states that do the worst job of maintaining bridges get the most money, said Pete Weykamp of the New York Department of Transportation. He blamed the trend on the fact that no specific agency has an apparent motivation to keep bridges in good condition.

"There isn't any particular industry that stands to gain from preservation," he said. "There are contractors, for example, but if you think of contractors in your home, they'd rather break your wall down and start anew than work with what's there."

Instead of waiting until bridges deteriorate and then repairing them, states need clear strategies for keeping bridges in good shape, he said.

Preserving a bridge can be done simply by taking care of a limited number of bridge parts, said Sandra Larson of the Iowa Department of Transportation. For example, treating the bridge's joints and outer surfaces with water sealants and other protective agents could significantly extend a bridge's useful life.

Federal lawmakers continue to debate whether bridge-safety funding should rise or be more strictly regulated, said Robert Kirk, a transportation specialist with the Library of Congress' Congressional Research Service. Some states have received federal highway funds but transferred the money to other projects, he said, a tactic that has some lawmakers calling for a ban on the practice until those states can bring their number of structurally deficient bridges to zero.

Kirk called the target "highly unlikely."