Sometimes the truest picture of the economy can be assembled not from the top down but from the bottom up. While higher oil prices are getting a lot of the blame for the recent "soft patch" of growth and job creation, there are other choke points that also are responsible for the slowdown.

Take a look at some local newspaper headlines from around the country over the past few weeks:

"Cement shortage delays projects" -- St. Petersburg Times

"Shipping by rail still off track" -- The Dallas Morning News

"Trucker shortage hurts freight lines" -- The Denver Post

Although each paper is reporting on events within its circulation area, the trends uncovered are having a nationwide or, in some cases, worldwide impact. Even as oil prices fell Tuesday for the third straight day, prices of other commodities are still rising and the transportation infrastructure is constricting.

Take the cement shortage. It started in Florida but it has spread nationwide. The building boom in China is diverting supplies that used to come to the U.S., which imported 22% of its needs last year.

Largely as a result, 41% of homebuilders couldn't get enough cement last month, up from just 3% in March, according to a survey by the National Association of Homebuilders (NAHB). The survey also found 26% of builders experienced shortages of gypsum wallboard, up from 16% in March, and one-fifth needed more insulation, twice the level of March.

Meanwhile,

Lafarge North America

(LAF)

,

Texas Industries

(TXI)

, and

Florida Rock Industries

( FRK) all say they are raising prices for cement and other materials even as they struggle to meet demand. It's been a great business to be in this year, with Florida Rock shares up 25%, Texas Industries up 17% and Lafarge, the biggest player, up 8%.

Rising prices for supplies tacked $5,000 to $7,000 onto the average cost of building a new home in July and shortages slowed down the pace of construction, the NAHB said.

"Left unchecked, these factors could result in serious disruptions to the housing market," said NAHB chief Jerry Howard.

That's exactly the kind of capacity constraint that can keep the economy from adding jobs and growing at the highest sustainable rate. Productivity, output and labor demand could decline even though there's plenty of demand for goods and services.

"If these shortages and supply constraints continue, it will eventually affect the ability of the economy to produce goods, which can also drive prices up," said Brian Wesbury, chief economist at Griffin, Kubik, Stephens & Thompson.

Wesbury maintains a long-held (and somewhat controversial) view that the

Federal Reserve

is creating imbalances by keeping real rates too low and needs to raise rates to prevent inflation from flourishing.

To be sure, there have been few signs of slowing homebuilding yet. Housing starts increased to a seasonally adjusted annual rate of almost 2 million units in July, according to NAHB. That was up 8% from June and almost 5% from a year earlier. And demand has been brisk, with new home inventories at a 40-year low in June. On Wednesday, the government will report new-home sales for July, which are expected to slow only slightly to 1.29 million from 1.33 million.

Can't Get There From Here

The cement shortage is being exacerbated by a shortage of ships to carry imported cement and the rest of transportation infrastructure around the country is straining.

As the

Denver Post

reported, there aren't enough drivers to meet the hiring needs of trucking companies like privately held

HVH Transportation

,

Swift

(SWFT)

or

Knight Transportation

(KNGT)

. The total tonnage of freight carried by trucks is projected to rise 4% this year after gaining only 3% over the previous two years.

SCS Transport

(SCST)

, a Kansas City, Mo.-based trucking firm, which said Monday it would miss third-quarter earnings estimates, tried to argue that demand has slowed. But industry analysts and larger competitors said demand was still heavy and SCS had gotten caught giving overly aggressive guidance.

Rail lines also are jammed this summer -- a period that is typically off-peak for freight carriers. Routine trips just across the city of Houston that used to take a day or two have stretched a week for some manufacturers in need of raw materials, the

Dallas Morning News

reported.

As the delays started spreading, Roger Nober, chairman of the Federal Surface Transportation Board sent a letter to rail companies in June demanding to know what plans they had for relieving congestion.

The demand surge is "unprecedented" since 1980, when Congress deregulated the rails and allowed companies to decide where to run lines and how much to charge, Nober wrote. The deterioration of on-time statistics at the rail companies "raises concerns about their ability to meet the ever increasing services demands being placed on them," he added.

The crunch "demonstrates the fundamental importance of freight rail services to our nation's economic health," Nober wrote.

If that's the case, the signals for growth are flashing yellow.

In keeping with TSC's editorial policy, Pressman doesn't own or short individual stocks. He also doesn't invest in hedge funds or other private investment partnerships. He invites you to send

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