Ontario Highway 7A

Lake Scugog was created when William Purdy and his sons dammed the Scugog River in Lindsay (Upstream from the current dam and locks) in 1834 to power his grist mill.[6] With the raised water levels, the highlands of Scugog Township became an island, separated from Cartwright Township to the southeast, and from Port Perry and Reach Township to the west. As a result, residents were forced to ferry across the lake during the summer and across the ice during the winter. The periods between were precarious, with many carts falling through the thawing ice and into the marsh. In 1852, Ontario County was formed, and residents began to petition the new government for construction of a bridge from Port Perry across to the island. Scugog Township passed Bylaw No. 2 on February 25, 1856, which granted $1000 towards construction of a floating bridge.[7]

The bridge proved to be an expensive burden, and for many years the responsibility for maintaining it was repeatedly shifted from township to county and back again. Ice would often carry away entire sections of the bridge during the spring thaw, requiring replanking or complete reconstruction. In the spring of 1876, work began to convert the first 180 metres (590 ft) of the Port Perry side of the floating bridge into a permanent embankment. Logs were placed along both sides the bridge and various materials piled between them, sinking it into the soft soil below. Earth laid over top to provide a stable surface. The process also increased the width of the roadbed from 3.7 metres (12 ft) to 5.5 metres (18 ft).[7][8]

The floating bridge, shortly after completion in the 1850s

Further construction on the Scugog Causeway met fierce opposition from county officials, who argued that the new method had not even faced a winter season. It took until July 1878 for work to resume, when Port Perry Reeve Joshua Wright managed to manipulate the county council, convincing them "to strike out the magnificent $150 [grant for seasonal maintenance which they had offered] and stipulate that 600 feet be filled in on the east end of the bridge." A contract for this work was tendered in June 1879, and completed one year later. Finally, in early 1885, work on the final 180 metres began. This work was completed in July, at which point repairs were carried out on the existing sections.[7]

Construction of the 4.2-kilometre (2.6 mi) Cartwright Causeway took place after nearly two decades of effort by its chief promoter, Joseph Bigelow. Bigelow witnessed the business opportunity that the Scugog Bridge opened up, and wished to construct a second structure towards Blackstock, opening the Port Perry markets to the fertile agricultural land of Cartwright Township. He first approached the Ontario County council in 1872 with his proposal, but was refused the funding. The council agreed to set up a committee, through which Bigelow sought out investors. In 1882, the Lake Scugog Marsh Lands Drainage Company, which had purchased the marshlands south of the proposed causeway, approached Bigelow with an offer to build his causeway as part of their plans to drain the marsh. They required a small investment in order to proceed with the work, but council ultimately refused even this, forcing the company to sell off its lands.[9]

Undeterred, Bigelow continued to accrue funds from other level of government and surrounding townships. By 1889, he had enough to begin work. Unlike the Scugog Bridge, Bigelow ensured that his structure would be permanent from the beginning and constructed a majority of the causeway by removing the top layer of peat from the marsh, piling logs in lengthwise approximately a metre deep and covering the exposed surface with the same depth of earth. By early 1891, the causeway was completed, and shortly thereafter trees were planted along both sides.[9]

The combined 12-kilometre (7.5 mi) route quickly grew to be the main east–west transportation corridor in the area. However, due to the soft soils and clay on which the causeway was built, it sank at a continuous rate and still required maintenance to keep it above water during the spring thaw. In 1928, both causeways were reinforced, widened and heightened in response to growing automobile usage.[7]

Reconstruction of the Cartwright Causeway in late 1960

On November 29, 1933, the Department of Highways assumed Lansdowne Street in Peterborough as Highway 7A, providing an alternate route south of downtown.[2] At that point in time, Highway 7 entered Peterborough by following Lindsay Street east from Fowlers Corners to Chemong Road and curving southeast. It followed Chemong Road to Reid Street, which it then followed south. The route proceeded west along McDonnel Street and south along George Street to Lansdowne Street, which it followed east out of Peterborough. Highway 28 entered Peterborough from the west along Lansdowne Street, curving north at what is now Ford Street. It followed this onto what is now Clonsilla Avenue, and curved east onto Charlotte Street, which it followed to George Street. Highway 7A thus provided a direct route between Highway 28 and Highway 7 south of Peterborough.[10]

In May 1938, Highway 7A was extended west to Highway 7 and Highway 12 at Manchester via Bethany and Port Perry.[11] This created a concurrency with Highway 28 and brought the length of the highway to 68 kilometres (42 mi). The new extension was a gravel road between Port Perry and Highway 28,[10] but the section between Port Perry and Blackstock was paved by October 1939.[11]

In late 1954, Highway 115 was opened between Highway 35 at Enterprise Hill and Highway 28 south of Springville. As a result, Highway 7A was rerouted concurrently along a short section of the new highway. Several highways were rerouted in 1960, including Highway 7, which was redirected at Fowlers Corners to curve south and meet Highway 28 near Springville; the former route became Highway 7B.[12] During the spring of 2003, Highway 7A was truncated at Highway 115 near Cavan, taking on its current routing.[3][13]

During the late 1950s, spring flooding began to become problematic on both causeways, prompting the Department of Highways to reconstruct them and the approaches. Soil investigations were carried out over the length of the road in mid-1959, and in August 1960 contracts were tendered for construction. The existing causeways were both closed as the adjacent marsh was excavated up to 6 metres (20 ft) deep. Nearby properties were purchased for the sole purpose of excavating for earth for fill, which was trucked at a continuous rate. Over 8,100,000 cubic feet (230,000 m³) of organic material was removed from the marsh and 12,494,574 cubic feet (353,806.9 m³) of fill placed over several years of construction. As a result of this, the roadbed no longer sinks into the marsh and spring melt no longer poses an issue.[14]