How close are you to Coffeyville? At the city library they have several diaries published in the Kansas Historical Quarterly. As a matter of fact I recently photocopied a few pages of Caldwells diary from June 12 through June 20 relating to the crossing of the verdigree. Caldwell records being at 36 59'31.3 on the 12th then they set up an astronomoical station 57 3/4 miles from the start point and about 19 to 20" north of the 37th parellel.
I didn't find any index at the library for the quarterly, though they are bound by year with a title page stating the years contents. I ran across three diaries I believe in the 1930's-40's.