The Union Canal was a towpath canal that existed in southeastern Pennsylvania in the United States during the 19th century.
 First proposed in 1690 to connect Philadelphia with the Susquehanna River, it ran approximately 82 mi from Middletown on the Susquehanna below Harrisburg to Reading on the Schuylkill River.
The Hertford Union Canal or Duckett's Canal is a short stretch (c. 1.5 km) of canal in the London Borough of Tower Hamlets in East London.
 It connects the Regent's Canal to the Lee Navigation.
 It was opened in 1830 but quickly proved to be a commercial failure.
 It was acquired by the Regents Canal Company in 1857, and became part of the Grand Union Canal in 1927.
Rickmansworth is a small town in south-west Hertfordshire, England, situated approximately 20 mi northwest of central London and inside the perimeter of the M25 motorway.
 The town is mainly to the north of the Grand Union Canal (formerly the Grand Junction Canal) and the River Colne.
 The nearest large town is Watford, approximately 5 mi to the east.
 Rickmansworth is the administrative seat of the Three Rivers District Council; the local authority is named from the confluence of three rivers within Rickmansworth's borders; the River Gade and the Grand Union Canal join the upper River Colne near Rickmansworth's eastern boundary and are joined by the River Chess near the town centre from where the enlarged Colne flows south to form a major tributary of the River Thames.
 The town is served by the Metropolitan line of the London Underground and Chiltern Railways from London Marylebone to Aylesbury.
Parnall's Canal was a half mile long canal that was built in Cornwall in about 1720 near St Austell.
 It was closed due to a rock slide in about 1732.
 It was one of only five canals to be built in Cornwall, the others being the St. Columb Canal from Mawgan Porth to St. Columb, the Liskeard & Looe Union Canal, the Par Canal from Pontsmill to Par, and the Bude Canal.
The Leicestershire and Northamptonshire Union Canal is a canal in England that is now part of the Grand Union Canal.
The Grand Union Canal was a canal in England from Foxton, Leicestershire on the Leicestershire and Northamptonshire Union Canal to Norton Junction, close to Long Buckby Wharf on the Grand Junction Canal.
 It now forms the first 23 miles of the Leicester Section, a branch of the much bigger modern Grand Union Canal.
The Linlithgow Union Canal Society is a waterway society and a Scottish registered charity based at Linlithgow Canal Centre on the Union Canal at Linlithgow, West Lothian, Scotland.
 Also known as "LUCS", it was founded in 1975 by Melville Gray to "promote and encourage the restoration and use of the Union Canal, particularly in the vicinity of Linlithgow".
The Middlewich Branch of the Shropshire Union Canal is located in Cheshire, in the north west of England, and runs between Middlewich, where it joins the Trent and Mersey Canal, and Barbridge Junction, where it joins the main line of the Shropshire Union Canal.
 It is 10 mi long, and was planned as part of the Chester Canal, which was authorised in 1772, but the company ran out of money, and construction did not begin until 1827.
 The Trent and Mersey insisted that there should be no direct connection at Middlewich, and instead built the short Wardle Canal to join the two, charging large compensation tolls for traffic passing along it.
The Columbia Canal is the surviving canal of a series of canals built by the State of South Carolina in 1824 using the labor of indentured Irishmen to provide direct water routes between the upstate settlements and the towns on the fall line.
 It is on the Congaree and Broad Rivers in Columbia, South Carolina.
 It is the focal point of the Riverfront Park in Columbia.
 The canal is now used to generate hydroelectric power by the South Carolina Electric & Gas Co.
Barbridge Junction (grid reference [ SJ612570] ) is the name of the canal junction located at Barbridge, Cheshire, where the Shropshire Union Canal Middlewich Branch terminates and meets the Shropshire Union Canal main line.

Question: Which was built first, Union Canal or Columbia Canal?
Answer: Union Canal