Ancestry's title for this newly digitized database is "Canadian Border Crossings, 1895-1956". From where I sit it's more like US border crossings. It records mainly crossings into the US from Canada, although there are a few crossing in the other direction.
Confusingly this series has been known by the name of one of the crossing points, St Alban's, VT. The dates used by Ancestry, 1905-1956, are still those associated with the St Alban's data, even though there are crossings included prior to 1905. For example, at Calais, ME, some of the records date from as early as 1877. It's worth looking at the dates for the most likely crossing your ancestor would have used to see if records survive. The records for Ogdensburg, the nearest crossing to Ottawa, only start in July 1929. Below are the details of what's in the database from the Ancestry website.
- Calais, Maine (ca. 1906-Dec. 24, 1952) (also includes a few arrivals from 1877 to 1905)
- Van Buren, Maine (ca. 1906-Dec. 24, 1952)
- Vanceboro, Maine (ca. 1906-Dec. 24, 1952) (also includes a few arrivals from 1888 to 1905 and a few arrivals at Halifax, Nova Scotia and St. John, New Brunswick)
- Fort Fairfield, Maine (ca. 1909-Apr. 1953) (also includes a few arrivals at Easton, ME, Houlton, ME, Boston, MA, and Buffalo, NY and a few alien departures)
- Eastport, Fort Kent, Lubec, and Madawaska, Maine (ca. 1906-Dec. 24, 1952) (also includes some departure records of U.S. citizens)
- International Falls, Baudette, Duluth, Mineral Center, Pigeon River, Pine Creek, Roseau, and Warroad, Minnesota (Jan. 1907-Dec. 1952) (also includes some departure records of U.S. citizens)
- Buffalo, Lewiston, Niagara Falls, and Rochester, New York (1902-1954)
- Hogansburg, Malone, Morristown, Nyando, Ogdensburg, Rooseveltown, and Waddington, New York (Jul. 1929-Apr. 1956)
- Newport, Vermont (ca. 1906-Jun. 30, 1924)
- St. Albans, Vermont (1895-1954)
- Babb, Montana (Jun. 1928-Oct. 1956)