The remainder of Highway 29 remained until 1998, when responsibility for maintenance of the route was transferred to the United Counties of Leeds and Grenville.

Proceeding generally in a northwest direction, the former route travelled one block before splitting around the Leeds and Grenville County Court House, a National Historic Site.

[4][6] Highway 29 continued into Elizabethtown-Kitley, where some low-density development extended along the route as it transitioned to a rural farmland setting.

[6] After passing through the communities of Tincap and Spring Valley, it curved west briefly before returning towards the northwest.

It turned north and later entered the community of Newbliss, curving northwest and returning to farmland shortly thereafter.

At the hamlet of Shanes, the former highway intersected Kitley–South Elmsley Townline Road and crossed into the municipality of Rideau Lakes.

It meandered northeast approaching the outskirts of Smiths Falls, before crossing into the town 100 metres (330 ft) south of Van Horne Avenue.

[12] Responsibility was assumed by the DPHO for the upkeep of the 49.1-kilometre (30.5 mi) southern portion of the road, within the United Counties of Leeds and Grenville, on May 11, 1927.

That year saw the route redirected along what is now Christian Street along the western edge of the town, much to the chagrin of local residents.

[13] On January 9, 1936, it was announced that the 26-kilometre (16 mi) Franktown Road, connecting Smiths Falls with Carleton Place, would be improved and assumed as a provincial highway.

[16] The majority of Highway 29 was a gravel road when it was assumed; by 1927, it was paved through Smiths Falls, between Carleton Place and Almonte, and through Pakenham.

[17] Paving operations between Brockville and Smiths Falls commenced in 1929,[18][19] with the portion between west of Spring Valley and Forthton being completed that year.

[20] Paving north of Brockville to the existing pavement west of Spring Valley was completed in 1930, and between Newbliss and Smiths Falls in 1931.

The northern 10 km (6 mi) of the route, near Arnprior, were paved in 1932;[25] a short segment between Almonte and the Indian River in 1934.

[34] The department performed a series of renumberings similar to these recommendations following the extension of Highway 43 on September 8, 1961.

[1][38][39] As part of a series of budget cuts initiated by premier Mike Harris under his Common Sense Revolution platform in 1995, numerous highways which were no longer significant to the provincial network were decommissioned and responsibility for the routes transferred to a lower level of government, a process referred to as downloading.