KDHE uses a number of sources of data including the number of cases each state and country has and whether there are reports of widespread community transmission to make the determination. A formula is used to evaluate new cases in states over a two-week period, then it is adjusted for population size to provide a case rate per 100,000 population. This provides a number that can then be compared to the rate in Kansas. States and countries with significantly higher rates -- approximately 3x higher -- are added to the travel quarantine list.
Currently, KDHE does not consider travel within Kansas as a criteria for travel-related quarantine. However, a local health officer may choose to include this as a criteria so you should be aware of your local isolation and quarantine criteria.