To most motorists in Louisiana, the only visible parish roads with numerical designations are the few that appear on state-maintained signage at various Interstate Highway exits.

This list includes all nine instances where a parish road intersects an Interstate Highway and features MUTCD standard signage installed by the Louisiana Department of Transportation and Development (La DOTD), the state's highway agency.

Caddo Parish Road 16 (PR 16) runs 6.20 miles (9.98 km) in an east–west direction from LA 1 north of Myrtis to US 71 in Mira.

PR 16 is only signed from intersecting state highways by La DOTD.

It is also signed by La DOTD immediately north and south of this interchange, though no signage has been posted on the state highways that PR 106 connects to.

Livingston Parish Road 45 (PR 45) runs 8.94 miles (14.39 km) in a north–south direction from LA 42 at Colyell to US 190 at Satsuma.

Natchitoches Parish Road 547 (PR 547) runs 8.80 miles (14.16 km) in a general east–west direction from LA 1222 northeast of Robeline to PR 441 (Johnson Chute Road) west of Natchitoches.

PR 547 is only signed with standard markers at its interchange with I-49 by La DOTD.

PR 620 is only signed with standard markers at the junction of LA 478 and Flora-Natchez Road near the former's interchange with I-49.

PR 820 is only signed with standard markers at its junction with LA 490 near an interchange with I-49.

Natchitoches Parish Road 829 (PR 829) runs 5.72 miles (9.21 km) in an east–west direction from the junction of LA 493 and Forest Service Road 339 (FS 339) south of Montrose to LA 119 in Derry.

PR 829 is only signed with standard markers at its junction with LA 119 near an interchange with I-49.

PR 117 is signed by La DOTD at its interchange with I-20 but only on the secondary exit ramp signage.

The route is also signed in a few locations by the Webster Parish Police Jury.