The Great Black Swamp of Ohio
yes, malaria was present in the US in the "good old days". And what stopped it was draining the swamp, not DDT.
Although much of the area to the east, south, and north was settled in the early 19th century, the dense habitat and difficulty of travel through the swamp delayed its development by several decades. A corduroy road (from modern-day Fremont to Perrysburg) was constructed through the Maumee Road Lands in 1825 and paved with gravel in 1838, but travel in the wet season could still take days or even weeks. The impassibility of the swamp was an obstacle during the so-called Toledo War (1835–36); unable to get through the swamp, the Michigan and Ohio militias never came to battle. Settlement of the region was also inhibited by endemic malaria. The disease was a chronic problem for residents of the region until the area was drained and former mosquito-breeding grounds were dried up.