It's easy to identify industry bellwethers. They are often the largest or most dynamic leaders in their sectors, tipping the rest of the market off on the state of the industry. A bellwether's strong or weak report can move the shares of its rivals. It's just what an industry tastemaker does.

What about corporate America? There are several stocks that provide a good glimpse into the state of our country's economy. Let's take a look at some of these companies that investors should be watching even if they don't own them.

Cintas (CTAS -0.17%)
The leading provider of workplace uniforms is a pretty fair proxy for hiring practices. If companies are increasing or decreasing the number of employees it should reflect in the number of uniforms that Cintas is providing.

Cintas does more than just corporate identity apparel. It also provides rubber entrance mats, bathroom supplies, and other company essentials. 

Cintas reported quarterly results on Monday. Revenue only inched 0.2% higher to $1.1 billion, but that's not a fair indicator of its actual performance. It unloaded its document shredding service back in April. Back that out and organic revenue moved a more encouraging 7.2% higher. 

This doesn't mean that companies have 7% more uniformed workers around. Prices move up. Cintas gets companies to spend more on other product lines and services. Cintas also gobbles up market share. There will never be a perfect proxy for a country's economy, but Cintas comes fairly close.

ManpowerGroup (MAN 1.09%) 
Naturally there's plenty of hiring out there for jobs that don't involve wearing uniforms that Cintas cleans and replenishes every week or so. That's where staffing specialists kick in as a great dipstick for the economy. 

Through ManpowerGroup's many subsidiaries -- Experis, Manpower, Right Management, and ManpowerGroup Solutions -- it helps source and develop talent for 400,000 clients worldwide. It also connects more than 600,000 individuals a year to workplace opportunities. 

ManpowerGroup reports fresh financial results later this month. Analysts see revenue climbing at a 5% clip this year and again come 2015. 

Caterpillar (CAT -0.55%)
Let's talk construction equipment. Caterpillar is the major player in construction and mining equipment. From backhoes to excavators, Caterpillar is responsible for a lot of moving ground.

Caterpillar saw sales of its heavy machinery slide 10% in August, but that was the handiwork of weakness abroad. Machinery sales actually improved 8% in North America. If Caterpillar's holding up well it's a good sign that construction activity is picking up. That naturally is a fair indicator of near-term optimism.  

FedEx (FDX 1.37%) 
The ability for companies and consumers to spring for speedy parcel and document deliveries is another great proxy for the economy that investors can find in FedEx's results.

Analysts see revenue climbing 5% in its latest fiscal year that began in June. FedEx also announced a couple of weeks ago that its shipping rates will be increasing by nearly 5% across many categories, but let's not assume that the increase in rates is what's driving revenue growth at FedEx. As the economy improves more people turn to FedEx.

Netflix (NFLX -9.09%)
Jim Cramer isn't always right, but he nailed it last year when he called Netflix a stealth housing play. 

"As more homes are built, cable, dish and Netflix get hooked up," he said on CNBC's Mad Money. "It's a natural tailwind. When you buy that new TV it has that Netflix clicker on the bottom."

Netflix may be a better gauge than cable or satellite television subscriptions for the state of the housing industry these days. The pay TV industry has actually been taking a breather lately, as younger home owners cut the cord and rely on streaming content. Netflix is now the better indicator.