1. Bridge Photos MINNEAPOLIS (March 23) - Old photos of the Interstate 35W bridge show two steel connecting plates were visibly bent as early as 2003 - four years before the span collapsed into the Mississippi River, killing 13 people.

2. Gusset plates that are slightly bent are seen in the center of this June 2003 photo of the Interstate 35W bridge in Minneapolis, Minn. The bridge plunged into the Mississippi River during rush hour on Aug. 1, killing 13 people. The plates are in areas believed to be among the first points of failure on the bridge.

3. These 2003 photos of the gusset plates, which hold the beams together at two separate points, were released this month by the National Transportation Safety Board, which is investigating the bridge's collapse.

4. The NTSB said Jan. 15 that steel plates used to build the bridge were probably too thin to hold the bridge together.

5. The Interstate 35W bridge is shown under construction July 1967. In a preliminary report, the NTSB found that the bridge should have been built with inch-thick steel plates instead of the half-inch plates that were used. The finding surprised many who believed that the collapse was related to the bridge's age.

6. Rescue workers search for victims after the collapse. Investigators found 16 fractured gusset plates, which are steel structures that hold together the girders used to carry the weight of a bridge, in the wreckage.

7. Survivors look on after the collapse. Soon after the accident, many people came to believe that age and maintenance were the causes, and officials from across the country called for increases in bridge maintenance budgets. The gap between public perception and the NTSB's finding have added to a political fight over the collapse and its cause.

8. Shortly before the accident, Republican Gov. Tim Pawlenty vetoed a gas tax increase that would have paid for highway and bridge work in Minnesota. Democrats supported the tax hike. In December, the Democrat-controlled legislature hired a law firm to probe whether the state's government played a role in the collapse. Sources: AP, nytimes.com