Tara Junction, located west of the Co.Meath town of Navan is where the independent 1872 built branch line from Kingscourt joined the former Great Northern Railway's line from Drogheda to Oldcastle, opened in 1863. Originally a double track junction called Kingscourt Jct, and latterly Navan West or Nevinstown Jct, the Kingscourt line, operated by the Midland Great Western, ran parallel to the GNR's line from Oldcastle where it then diverged to the south towards Clonsilla at the former Navan Junction Station. Passenger services on the former MGWR line from Clonsilla through to Navan and Kingscourt ceased in 1947, and likewise on the Drogheda to Oldcastle branch in 1959.
CIE then closed the lines from both Oldcastle and Clonsilla to Navan in 1963, but retained the through route from Kingscourt to Drogheda for goods and gypsum traffic. The Tara Mines began operation in 1977 west of Navan town and in the same year a spur was built on the former Oldcastle branch into the mine complex which diverged from the Kingscourt branch at the former Nevinstown Jct, now renamed 'Tara Junction'. Gypsum traffic from Kingscourt ceased in 2001 and since then Tara Junction has been disconnected, the branch having seen its last weed spraying train in 2002. Only the line from Tara Mines through Navan to Drogheda remains in use for zinc ore traffic to Dublin Port.