NEW YORK (FORTUNE) - Consider the Fortune 1000 as a very long ladder.

The companies near the top are duly celebrated. But drop down a ways and you'll find new names jostling to be America's great corporations of the future.

Full list: FORTUNE 1000 1. Exxon Mobil 6. ConocoPhillips 2. Wal-Mart 7. GE 3. GM 8. Citigroup 4. Chevron 9. AIG 5. Ford 10. IBM Top companies in your state Top-performing companies • Most profitable • Best investments • Fast growing • Big employers Related stories: • Shakeup at the top • FORTUNE 500 roars ahead • Exxon Mobil: A big target

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This is where, as one CEO recently put it, you can watch a company before the law of big numbers starts to slow things down. Change happens fast, upsets are still possible, and momentum hints at what's to come.

Many of the six companies portrayed here are on the Fortune 1,000 for the first time; each grew revenues by 30 to 85 percent last year, making them some of the fastest growing companies on our list.

And, like every great company, each one has a compelling story about real people, and a few bits of trivia that might surprise you.