Typically, Pitkin County addresses are assigned using the Century System where address numbers are based on fractions of a mile starting from the origin of a roadway to the start of a property’s driveway. The theory behind this is that anyone in a vehicle could find their destination based from an odometer reading.
Parity (Even/Odd determination) is normally based on compass direction from the center of the street, with addresses on the North or East sides receiving even numbers and those on the South or West receiving odd numbers. However, many streets in the county have been assigned using the Left/Odd and Right/Even methodology. Address Services makes the Even/Odd determination based on Public Safety requirements.
For more information please see the Titled Address Standards 9.08.080: ADDRESS/NUMBERING SYSTEM