Growth in manufacturing and consumer spending has helped this unglamorous industry prosper.

Those big rigs you see rumbling down the freeway are a sign of good times.

Trucking is now the fastest-growing small-business industry in the U.S., thanks to a robust economy and expanded options for small-business loans and financing.

Two kinds of small businesses in trucking posted the biggest jumps in revenue in the 12-month period ending May 31, according to a report released this month by Sageworks, a financial analysis software company.

General freight trucking, which covers small businesses that transport a wide range of merchandise, was at No. 1, recording a nearly 25% uptick in sales, the report said.

At No. 2 was building and construction, at 19%, followed by specialized freight trucking, which covers tankers and refrigerated trucks, at No. 3 with a 17% gain.

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