Oregon's 4th Senate district

District 4 of the Oregon State Senate comprises central Lane County centered around Eugene and Springfield.

It is currently represented by Democrat Floyd Prozanski of Eugene.

District boundaries have changed over time, therefore, senators before 2021 may not represent the same constituency as today.

From 1993 until 2003, the district covered eastern Washington County; from 2003 until 2013, it shifted to cover southern and eastern Lane County, including much of downtown Eugene, as well as northern Douglas County; and from 2013 until 2023, it stayed mostly the same while gaining some of southern Creswell and northern Roseburg.

It is substantially physically smaller and is centered around the downtowns of Eugene and Springfield while not containing any other incorporated cities.