30 January 1961 (The Fort Scott Tribune, Kansas)
The UFO was sighted over the Kansas City area and other nearby locales on 29/30 January 1961 (from 7:30 p.m. to 1:30 a.m.):
Quote from the article:
“The Federal Aviation Agency station at Hill City watched the object from 11:30 p.m. to 1:30 a.m. It was northeast of that station.”
NOTE: The newspaper date is 30 January 1961.
Satellite photo of Kansas City, Kansas (tageo.com)