On this date, May 1, 1865, A military post is established in Sioux Falls by Co. E, 6th Iowa Cavalry.

Source: Minnehaha County History.

On this date, April 28, 1910, the temperature hit 98 degrees in Sioux Falls, the warmest April temperature ever recorded in the city. 

Source: http://www.crh.noaa.gov/fsd/?n=fsdtrivia04

On this date, April 18, 1956, the Sioux Falls Weather Service bureau received its first weather radar, a WSR-1, which came out of a World War II aircraft. 

Source: http://www.crh.noaa.gov/fsd/?n=fsdstationhistory

(Sorry for the multiple posting. It's been a busy week.)

April 3

On this date, April 3, 1936, the coldest temperature ever recorded during the month of April at Sioux Falls occurred, when the temperature fell to just 4 degrees F above zero.

Source:   http://www.crh.noaa.gov/fsd/?n=fsdtrivia04

April 4

On this date, April 4, 1881, 40,000 cattle were represented by the Black Hills Stockgrower's Association.

Source: http://www.southdakotastockgrowers.org/history.htm

April 5

On this date, April 5, 1862, the Territorial Legislature passed an act establishing Lincoln, Minnehaha, Brookings, and Deuel Counties.

Source: Minnehaha County History, p. 19.

On this date, March 30, 1943, the warmest temperature ever recorded in the month of March, in Sioux Falls, occurred when the temperature hit 88 degrees Fahrenheit.

Source: http://www.crh.noaa.gov/fsd/?n=fsdtrivia03

An F-16C like those flown from by the SDANG's 114th Fighter Group in Sioux Falls.On this date, March 16, 1992, the S.D. Air National Guard 114th TFG was redesignated the 114th Fighter Group.

Source: http://www.state.sd.us/applications/MV91MVAInternetRewrite/default.asp?navid=23

The 114 TFG received the first of its F-16C/D fighters in August 1991 with the official conversion from the A-7 to the F-16 occurring on January 1, 1992 . The unit was redesignated as the 114th Fighter Group on March 16, 1992 and became a part of the newly formed Air Combat Command on June 1, 1992 .

According to the National Weather Service, on February 23rd, 1981 the high temperature in Sioux Falls soared to 70 degrees. That tied the record set on the same day in 1958 for the warmest temperature on record in Sioux Falls for the month of February and is also the earliest in the year that the temp has hit 70 degrees.

Source: http://www.crh.noaa.gov/fsd/?n=fsdtrivia02

On this date, February 9, 1948, Time magazine reported on Sioux Falls pathologist Albert M. Harris' quest for a test that would indicate if a person had cancer or not.

Source: http://www.time.com/time/archive/preview/0,10987,856030,00.html

Some scientists' interest in cancer is more than scientific. Quiet, balding Pathologist Albert M. Harris was one of those. Day after day he worked in the laboratory of the Sioux Valley Hospital at Sioux Falls, S.Dak. His father, also a physician, had had cancer. Young Dr. Harris was looking for a quick and sure test for the disease.

The clue, he thought, lay in an enzyme called hyaluronidase, which exists in the testes, eyes, spleen, skin. He believed that it exists in large amounts in most cancers. He devised a urine test: the enzyme is extracted from the urine with ether, then mixed with a solution of fresh umbilical cord and rabbit serum. Two weeks ago, in the first issue of the new South Dakota Journal of Medicine and Pharmacy, he reported his findings: if the solution remains clear, the patient has the enzyme in his body in larger than normal amounts—and may have cancer. If the solution becomes cloudy, the patient is free from cancer. The test's* big advantage, according to Dr. Harris: it can be made in 24 to 48 hours, costs only $5, is 75% to 90% accurate in detecting suspected cancer.

In December, Dr. Harris tried the test on himself; the solution was cloudy. One day last month he became ill, was admitted as a patient to his own hospital. Other doctors tried the test on him again. This time, the solution was clear, but no one told him. Dr. Harris was taken to Bishop Clarkson Memorial Hospital in Omaha, Neb. There one day last week he died— from cancer of the brain.

^{*Cancer experts reserved judgment on the test's theory and effectiveness.}

Balloonist and skydiver Nicholas Piantanida.On this date, February 1 1966, balloonist Nicholas Piantanida of the United States (1933-1966) reached 123,800 ft (37,750 m) above Sioux Falls, South Dakota. He landed in Iowa. He died later that year in another attempt at a skydiving record.

Sources: Norris McWhirter's Book of Historical Records, by Norris McWhirter p. 176 http://books.google.com/books?ie=UTF-8&hl=en&vid=ISBN1852278943&id=_AvhZNnPjWoC&pg=PA176&lpg=PA176&dq=%22February+1%22+%22South+Dakota%22+history&prev=http://books.google.com/books%3Fq%3D%2522February%2B1%2522%2B%2522South%2BDakota%2522%2Bhistory%26lr%3D%26start%3D20&sig=Sn8PfvGeOWIMwyyiZslMNU6B-pw and http://www.gasballooning.net/The%20QinetQ%20Flight.htm
One of Piantanida's balloons.

A chilling excerpt from gasballooing.net re Piantanida's flight:

As Piantanida prepared to step out of his balloon gondola for his long freefall back to Earth, he found that he couldn't disconnect his pressure suit from the gondola's oxygen supply.

"The next task was to disconnect his on-board oxygen unit, which would effectively sever him from any physical connection to the gondola. But when he tried to turn the valve that would release the oxygen hose, he found that it wouldn't turn. He jiggled it an applied all the pressure he could to try to move it, but it was frozen. And with the pressure gloves on his hands, he did not have the dexterity to do anything very fancy. He kept cranking on the disconnect valve, but it would not budge.

"As he worked, he kept up a chatter with his ground crew. "Disconnect, having problem with oxygen...disconnect...Going overtime. Ground Control, do you read me? We've got problems." "Piantanida's breath came heavy and rasping through the receivers on the ground. "Isn't this a bitch...Can't disconnect the oxygen....I don't believe it, I can't separate the hose."

Finally, the ground crew chief, Ed Yost, inventor of the modern day hot-air balloon, knew actions had to be taken. Piantanida would not be able to jump from the gondola as originally intended with the oxygen hose still connected. The only way to bring Piantanida home would be to separate the gondola with Piantanida in it, from the balloon and let it free-fall tens of thousands of feet into thicker air before opening a main gondola chute.

Piantanida, unable to strap his seat belt back on with his pressure gloves on, sat back onto his seat at 123,500 feet and braced his feet against the sides of the gondola. Ed Yost gave a countdown from ten to one over the radio before transmitting the command that would cut Piantanida and the gondola away from the balloon.

"The Second Chance [at skydiving from a balloon in the stratosphere] was falling like a rock. As he braced himself, Piantanida thought of his daughter, and tried to imagine her at age 18 as she opened the letter [he left for her in the event of his death]. The gondola was in freefall for a full 35 seconds, but to Piantanida's tremendous relief, there was no tumbling of spinning at all. The box just dropped straight down in the exact attitude it had assumed beneath the balloon. But his worries were far from over. The chute would open at 97,000 feet and he was prepared for a violent opening shock. He was falling at 600 MPH.

" Then it came. The chute was open and Piantanida was still in the gondola. He hadn't fallen out and he hadn't been blown through the floor. In fact, as it turned out, the shock wasn't really that much worse than the normal opening of a parachute in the lower atmosphere. "At 65,000 feet, Ed Yost broke the silence and asked how Piantanida felt. "I'm getting sick," was the answer. "These oscillations." As the gondola descended beneath the parachute, it swung wildly from side to side. "At 46,000 feet, Piantanida was still feeling sick. "How could one tiny but of stinking equipment screw up like that?" he asked no one in particular. Piantanida landed safely in an Iowa cornfield. Later, during a press conference to discuss the failure of his plans to skydive from the stratosphere, Piandanida explained "If only I had a damned $1.25 wrench, gravity would have done the rest." Unfortunately, Piantanida, landed with the gondola, but not the balloon. He was therefore ineligible for the world manned altitude balloon record. Piantanida died on August 29, 1966 after enduring a severe explosive decompression of his spacesuit on board Strato Jump III at 57,600 feet in his third quest to acquire the world record for a skydiving jump.