Below is a timeline of the routes by neilsmith749, which were eventually incorporated into the Ultra Mega Route (UMR) - the longest continuous route on the DLS.
Ogden and Oakwood Railroad (O&O RR), <kuid:95512:100543> July 2005
Gladston and Halden Railroad (G&H RR), <kuid:95512:100003> July 2005
GHOO Megaroute Final Edition (merger between O&O and G&H), <kuid:95512:101485> April 2006
Gilby and Wallace (G&W), <kuid:95512:101821> August 2006
Indiana Western (gfisher), <kuid:106916:1084> May 2007
UMR (merger between G&W and GHOO), <kuid:95512:102712> September 2007
Desert Mountain Plains (DMP), <kuid:95512:1030> July 2009
UMR2010 (merger between UMR and DMP), <kuid:95512:1095> July 2010
INDIANA WESTERN-2010 (neilsmith's upgrade of gfisher's 2007 route), <kuid:95512:100011> December 2010
UMR2010-MEGAMERGE-SUMMER (merger between IW and UMR2010), <kuid2:95512:1095:2> April 2011
SMITHVILLE CLASSIFICATION FACILITY (the hump yard), <kuid:95512:100030> April 2011
UMR2011-MEGAMERGE-SUMMER (merger between previous route and Smithville), <kuid2:95512:1095:3> May 2011
UMR-TS12-SUMMER (upgraded to TS12 standards), <kuid:95512:100024> September 2011
UMR-2013-SUMMER-MULTIPLAYER (several changes to layout for enhanced multiplayer), <kuid:95512:100096> April 2012
And that brings us to the present day. Note that intermediate routes, including season-change updates, were excluded. The KUIDs reported are the lowest available on the DLS; updates have been released for most of the routes.
I could not find the original Desert Mountain Plains by ESO on the DLS. If anyone knows when that was released, please share that information
Ogden and Oakwood Railroad (O&O RR), <kuid:95512:100543> July 2005
Gladston and Halden Railroad (G&H RR), <kuid:95512:100003> July 2005
GHOO Megaroute Final Edition (merger between O&O and G&H), <kuid:95512:101485> April 2006
Gilby and Wallace (G&W), <kuid:95512:101821> August 2006
Indiana Western (gfisher), <kuid:106916:1084> May 2007
UMR (merger between G&W and GHOO), <kuid:95512:102712> September 2007
Desert Mountain Plains (DMP), <kuid:95512:1030> July 2009
UMR2010 (merger between UMR and DMP), <kuid:95512:1095> July 2010
INDIANA WESTERN-2010 (neilsmith's upgrade of gfisher's 2007 route), <kuid:95512:100011> December 2010
UMR2010-MEGAMERGE-SUMMER (merger between IW and UMR2010), <kuid2:95512:1095:2> April 2011
SMITHVILLE CLASSIFICATION FACILITY (the hump yard), <kuid:95512:100030> April 2011
UMR2011-MEGAMERGE-SUMMER (merger between previous route and Smithville), <kuid2:95512:1095:3> May 2011
UMR-TS12-SUMMER (upgraded to TS12 standards), <kuid:95512:100024> September 2011
UMR-2013-SUMMER-MULTIPLAYER (several changes to layout for enhanced multiplayer), <kuid:95512:100096> April 2012
And that brings us to the present day. Note that intermediate routes, including season-change updates, were excluded. The KUIDs reported are the lowest available on the DLS; updates have been released for most of the routes.
I could not find the original Desert Mountain Plains by ESO on the DLS. If anyone knows when that was released, please share that information