Most economic indicators suggest the economy is in full recovery.

But the second-quarter report from private company data tracker Sageworks shows some worrisome trend lines. Though the construction industry is clearly on fire with new building projects, sales in other key sectors are sputtering. Trucking, a useful bellwether because most companies in that industry are  small and respond directly to consumer demand for products and sevices, has seen growth slashed nearly in half over the past two years, according to its latest report, out Monday.

“If the trucking industry is doing well, growing revenues and hiring more employees, it often indicates that consumer demand is strong, and their appetite for buying is high,” Kevin Abbas, a Sageworks analyst, said in the report. “They’re the middle men between production and consumption. Good news for the trucking industry is good news for both U.S. retailers and U.S. manufacturers.” So when it's not doing well, as has been the case lately, many industries are probably feeling the pain.  

Sales for all private companies fell half a percentage point, to 8.3 percent, in June, compared with the same quarter a year ago. Manufacturing fared the worst, with sales decreasing 2.5 percentage points, to 7.1 percent, compared with the second quarter in 2013. Retail sales fell half a percentage point, to 6.2 percent, while wholesale sales fell nearly a full percentage point, to 6.7 percent, for the same period.  

Trucking sales declined 2 full percentage points, to 7.7 percent, compared with the second quarter of 2013. And sales fell almost in half, compared with 13.8 percent for the second quarter of 2012. And in an extremley worrisome development for large consumer purchases, sales for specialized trucking companies, which tend to transport awkward or large items such as refrigerators, washers, and dryers, have been trounced. Sales for these companies fell nearly in half, to 5.1 percent, compared with the second quarter in 2013, and by nearly two-thirds compared with the same period in 2012.

But all is not lost. Construction sales have been borne up significantly on the gusts created by the low-rate borrowing environment, which has encouraged house building, buying, and selling. Sales in the construction industry grew nearly a full percentage point, to 13 percent, in the second quarter, compared with a year ago, and more than two percentage points compared with two years ago.

On another bright note, private companies continue to reduce their debt loads, with debt to equity falling two-tenths of a percent, to 2.9 percent, in the second quarter compared with the same period a year ago. Although private companies also report a marked increase in the number of days it's taking to get paid, up to 46, from 37 in the second quarter of 2013.

Sageworks compiles its quarterly reports on the basis of the financial statements of approximately 1,000 private companies it analyzes every day.