Mann Mountain was opposite the mouth of the Matapedia River, with Flatlands straddling the eastern border; St. Jean Baptiste – Menneval, White's Brook were both along Route 17, nearer Kedgwick than Campbellton; the LSD of the parish of Eldon comprised the remainder of the parish.

[8] In the reform, Kedgwick annexed the community of Wyers Brook, properties on either side of Route 17 south from Glenwood, and all of the parish to the west;[5] the remainder became part of the rural district.

[6] The parish was named in honour of the Earl of Eldon,[9] Lord High Chancellor of Great Britain at the time of its erection.

In 1840 the eastern boundary was altered to run due south from the mouth of the Upsalquitch.

[13] In 1896 Eldon was reërected from Addington, with the eastern line now further east in its modern configuration.