Although the TCH network is strictly a transcontinental system, and does not enter any of Canada's three northern territories or run to the United States border, it does form part of Canada's overall National Highway System (NHS), which provides connections to the Northwest Territories, Yukon, and the border, although the NHS (apart from the TCH sections) is unsigned.

In much of British Columbia, Ontario, Prince Edward Island, and Newfoundland and Labrador, the Trans-Canada Highway system is still in its original two-lane state.

The British Columbia section of Highway 1 is 1,045 km (649 mi) long, beginning in Victoria at the intersection of Douglas Street and Dallas Road (where the "Mile 0" plaque stands), and ending on the Alberta border at Kicking Horse Pass.

While the only true freeway sections of the route are along the Regina Bypass, in Medicine Hat, and between Calgary and Banff, the whole highway is largely stoplight-free, with "split" at-grade intersections forming the vast majority of the junctions.

On January 10, 2016, the Nipigon River Bridge suffered a mechanical failure, closing the Trans-Canada Highway for 17 hours; the only alternative was to go through the United States, around the south side of Lake Superior.

Marie, the highway crosses the Montreal River Hill, which sometimes becomes a bottleneck on the system in the winter when inclement weather can make the steep grade virtually impassable.

However, a short section of the Central Ontario branch does pass through the rural northeastern edge of Durham Region at both Sunderland and Beaverton, which is officially part of the Greater Toronto Area.

[17][needs update] Once this project is complete, the disconnected sections of Autoroute 85 will be joined, and all of Quebec's Mainline Trans-Canada Highway route will be minimum four-lane freeway standards.

From Moncton, the highway continues southeast for 54 km (34 mi) to a junction at Aulac close to the New Brunswick–Nova Scotia border (near Sackville).

The terminus of the Trans-Canada Highway in Victoria, at the foot of Douglas Street and Dallas Road at Beacon Hill Park, is also marked by a "mile zero" monument.

[18][19] The usage of miles instead of kilometres at both designations dates back to when the Trans-Canada Highway was completed in 1962, prior to metrication in Canada.

Since it carries significantly less traffic than its more southerly counterpart, the Yellowhead is almost exclusively a two-lane highway in British Columbia and Manitoba, and is only partially a four-lane expressway in Alberta and Saskatchewan.

This highway first runs south of the Main TCH route between Kenora and Thunder Bay, passing through the town of Fort Frances on the U.S. border.

Many of the earlier highways in British Columbia were largely gravel and had many frequent inland ferry crossings at wide rivers and lakes.

While at the time it was considered a major improvement to the gravel roads and ferries it replaced, it was soon believed to be insufficient to handle the growing traffic volumes.

The four-lane Upper Levels Freeway was relatively-crudely constructed, with narrow lanes, low overpasses, and no proper merge ramps.

The opening of the Cassiar Tunnel in 1990 bypassed the last sets of signal lights in Vancouver, rendering the whole alignment of the Trans-Canada Highway through the Lower Mainland a freeway.

The older freeways in the Lower Mainland were largely built as a parkway design, with wide, forested medians and low overpasses (a road configuration that was common across North America at the time).

Plans for a freeway to bypass or eliminate traffic congestion and road hazards along the heavily-travelled route from Victoria to Nanaimo on Vancouver Island were cancelled during the recession that followed the 1987 stock market crash.

In Alberta, between 1964 and 1972, the Trans-Canada Highway was completely rerouted from its former two-lane alignment along the Bow River to a new, more direct, four-lane freeway between Banff and Calgary, resulting in the bypassing of several towns, such as Canmore.

In 2000 and 2001, Transport Canada considered funding an infrastructure project to have the full Trans-Canada system converted to limited-access divided highways.

Although construction funding was made available to some provinces for portions of the system, the federal government ultimately decided to not pursue a comprehensive limited-access highway conversion.

Prior to the start of the Great Recession in 2008, the highway underwent some changes through the Rocky Mountains from Banff National Park to Golden, British Columbia.

A major piece of this project was completed on August 30, 2007, with the new Park Bridge and Ten Mile Hill sections opening up 16 km (9.9 mi) of new four-lane highway.

As part of the Gateway Program, 37 km (23 mi) of congested four-lane Highway 1 freeway in Metro Vancouver were widened to an eight-lane buildout starting in 2012.

remains in its original two-lane state, and only about 15% of the mainline's length is composed of freeway comparable to that of the Interstate Highway System.

In 2012, a series of free public electric vehicle charging stations were installed along the main route of the highway by a private company, Sun Country Highway, permitting electric vehicle travel across the entire length, as demonstrated by the company's president, Kent Rathwell, in a publicity trip from St John's, NL, to Victoria, BC, in a Tesla Roadster.

[36] As of September 2021[update], British Columbia was planning on widening the 420-kilometre-long (260 mi) long section of TCH between Kamloops and Alberta to four lanes by 2050.

The project goals do not include an eventual freeway conversion, and it is likely that the signalized sections of highway in Kamloops, Salmon Arm, Revelstoke, and Golden will remain.

Apart from the major programs, many smaller-scale projects exist on the highway in order to rehabilitate the aging infrastructure or make minor traffic changes.