Although most railways of central and eastern Canada were initially built to a broad gauge, there were several, especially in Atlantic Canada and Ontario, which were built as individual narrow-gauge lines. These were generally less expensive to build, but were more vulnerable to frost heaving because vertical displacement of one rail caused greater angular deflection of the narrower two-rail running surface. Most of the longer examples were regauged starting in the 1880s as the railway network began to be bought up by larger companies.