The point-to-point routes used in the Iowa Tour were provided by ALK's CoPolot Live mobile navigation system. The optimal route begins on Pennsylvania Avenue in Des Moines, heading south towards Newton.
The full set of turn-by-turn driving directions is given in the following pdf file.
The driving times in Co-Pilot's directions include estimates for stops of various types, resulting in a guess of 72 hours and 47 minutes for a typical driver to cover the state.
