The impression that Kansas is losing population is probably due to the fact that most of Kansas (the rural part) is losing population.
"The rural population of Kansas continues to decline in a process known as rural flight. The past few decades have been marked by a migration from the countryside into the cities. Kansas now has more than 6,000 ghost towns and dwindling communities, while communities in Johnson County (home to metropolitan Kansas City) are some of the fastest-growing in the United States."[0]
"The rural population of Kansas continues to decline in a process known as rural flight. The past few decades have been marked by a migration from the countryside into the cities. Kansas now has more than 6,000 ghost towns and dwindling communities, while communities in Johnson County (home to metropolitan Kansas City) are some of the fastest-growing in the United States."[0]
[0] http://worldpopulationreview.com/states/kansas-population/