Midwest hybrid sales soared 57 percent, with the Toyota Prius and hybrid version of the Toyota Camry the most popular models, R.L. Polk & Co. said.
Oklahoma led all states with a 143 percent increase in hybrid sales, compared with 2006's first seven months, Polk said.
Hawaii was the only state to report a decline in hybrid sales, dropping 5.3 percent.
Hybrid sales rose 42 percent in the South, 49 percent in the Northeast and 52 percent in the West, Polk said.
While it was No. 2 in growth, the West led in total volume, anchored by No. 1 hybrid vehicle-registration state, California, Polk said.
"Hybrids are a bright spot" in an otherwise down U.S. auto market, with the category projected "to easily exceed 300,000 vehicles this year," or more than 2 percent of total U.S. vehicle sales, industry analysis Director Lonnie Miller said.
U.S. consumers bought 254,545 hybrids in 2006.
The growth in hybrid sales is in part due to high fuel prices, "differentiating themselves from other consumers and environmental activism," Miller said.
Hybrid sales will likely continue to grow nationwide, she said.
Celebrity Couples of 2014 [PHOTOS]