As transportation advocates push for bridge upgrades after the collapse in Washington state last week, it’s clear that some states have far more work to do than others.

Bridge inspection data reported to the Federal Highway Administration shows a wide variation in conditions of bridges across regions, both in terms of deterioration and outdated designs. Although states with some of the worst bridges stepped up efforts to fix or replace bridges in recent years, they continue to face an uphill battle as many aging structures long battered by harsh weather and heavy traffic begin to require repairs.

The majority of the nation’s bridges are at least four decades old, with many built during the 1950s and 60s. Since then, most areas experienced rapid growth, and along with it came more traffic than bridges were originally designed to accommodate. At the same time, some states went for long stretches without making major investments in bridge maintenance or repairs.

“States have had to make tough decisions and have had to decide between maintenance, repairs, re-decking or even closing bridges,” said Andy Herrmann, past president of the American Society of Civil Engineers.

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Bridges most in need of repairs are deemed “structurally deficient,” meaning they exhibit deterioration to at least one major component. These bridges receive higher priority for funding, but it doesn’t mean that they’re unsafe for travel.

Nearly 67,000 bridges nationwide are considered structurally deficient, or about 11 percent of all bridges recorded in federal data.

In Pennsylvania, 24.4 percent of bridges are structurally deficient – the nation’s highest percentage. Also high on the list are Oklahoma (22.6 percent) and Iowa (21.2 percent). (See full table below)

By comparison, bridges are generally in far better shape in states with newer infrastructure throughout the Sunbelt or western U.S.  Only 2.2 percent of bridges in both Florida and Nevada, for example, are structurally deficient.

Herrmann said bridges in the Northeast are most in need of upgrades because they’re often older and must weather harsh winter conditions.

Fixing decaying bridges is crucial. But Herrmann said regular maintenance is also key to saving taxpayer dollars down the road.

“It’s not something you can just fix overnight,” he said. “You have to keep at it.”

Since 2008, Pennsylvania pushed down its net total of structurally-deficient bridges by more than 700. But like other states, it faces a challenge in that new entries are added to the list even as upgrades are made.

The Pennsylvania Department of Transportation made progress in fixing bridges when it has had adequate resources, particularly with stimulus grants, said Kent Harries, an associate professor of structural engineering and mechanics at the University of Pittsburgh.

Gov. Tom Corbett and the legislature are weighing several options to boost funding for the state’s infrastructure, including a hike in the gas tax for the first time since 1997.

“Their attitude is nothing is off the table because the table is falling apart,” said Harries, who offered several reasons to explain the poor condition of Pennsylvania’s bridges.

For one, road salt crews use during the winter months causes bridges to wear faster. Those most in need of repairs tend to be concentrated in the western portion of the Commonwealth, but not enough funding is distributed to transportation districts covering these areas, Harries said. More recently, large trucks and heavy equipment traffic from the Marcellus Shale boom has taken a toll on some rural bridges.

Officials in Washington state say the bridge there collapsed when a truck hauling a large load hit a truss span of the structure. Former Washington Transportation Secretary Paula Hammond told Governing the bridge wasn’t in poor condition, but rather its small size and narrow lanes may have contributed to the accident.

The Skagit River Bridge was not structurally deficient, but was classified as "functionally obsolete,” meaning it was built to standards no longer used today.

This measure is also worth considering when assessing the overall condition of a state’s bridges.

About 14 percent of the nation’s bridges are considered functionally obsolete, according to federal data. More than half of bridges in the District of Columbia received this designation, followed by Massachusetts (43.2 percent), Rhode Island (33.7 percent) and Hawaii (31.7).

One problem Harries and other transportation advocates often cite is that the issue ends up on the back-burner in state legislatures, failing to gain any traction absent a major news event, such as the incident last week.

“You don’t get your name on bridge repair projects. It’s never been a really hot button issue,” Harries said.

Funding for bridge repairs similarly long remained stagnant in Oklahoma, responsible for the second-highest number of structurally deficient bridges.

"We were just falling further and further behind,” said Cole Hackett, spokesman for the Oklahoma Department of Transportation. “The money we did have had to be put to those bridges most heavily traveled."

In response, the legislature increased funding in recent years. Also, in her State of the State address earlier this year, Gov. Mary Fallin outlined an eight-year plan to repair all of the state’s structurally deficient highway bridges.

As more bridges are repaired, Hackett said he expects to see the tally of the state’s structurally deficient bridges to begin to trickle down.

Read our story on the disparity of bridge conditions between those on state and locally-owned roads

Bridge Inspection Data

The following data represents 2012 totals reported to the Federal Highway Administration.

Structurally deficient: Bridge had deterioration to one or more major components, but is not unsafe.

Functionally obsolete: Bridge was built using outdated standards, such as older design features.