Question: The Las Vegas and Tonopah Railroad was a 197.9 mile railroad.that ran northwest from a connection with the mainline of the San Pedro, Los Angeles and Salt Lake Railroad at Las Vegas, Nevada, the SPLA&SL railroad later became part of which freight hauling railroad that operates 8,500 locomotives over 32,100 route-miles in 23 states west of Chicago and New Orleans?
Context: The Los Angeles and Salt Lake Railroad (reporting mark SLR) was a rail company that completed and operated a railway line between its namesake cities, via Las Vegas, Nevada.  Incorporated in Utah in 1901 as the San Pedro, Los Angeles and Salt Lake Railroad, the line was largely the brainchild of William Andrews Clark, a Montana mining baron and United States Senator.  Clark enlisted the help of Utah's U.S. Senator Thomas Kearns, mining magnate and newspaper man, to ensure the success of the line through Utah.  Construction of the railroad's main line was completed in 1905.  Company shareholders adopted the LA&SL name in 1916.  The railway was also known by its official nickname, "The Salt Lake Route", and was sometimes informally referred to as "The Clark Road".  The tracks are still in use by the modern Union Pacific Railroad, as the Caliente, Sharp, and Lynndyl Subdivisions. The San Pedro and Southwestern Railroad (reporting mark SPSR) is an Arizona shortline railroad, currently operating from a connection with the Union Pacific Railroad (UP) at Benson, Arizona, seven miles to Curtiss, Arizona.  The SPSR formerly ran a total of 76.2 mi , with main track from Benson to Paul Spur, a location about 10 mi west of Douglas, as well as the Bisbee Branch which ran 5.6 mi to Bisbee, Arizona.  The SPSR is owned by David Parkinson's "Arizona Railroad Group".  David Parkinson has owned several other shortlines in California, such as the California Northern Railroad, under his ParkSierra Rail Group, now a part of RailAmerica.  The San Pedro and Southwestern "Railroad" commenced operations in November 2003 when it purchased the San Pedro and Southwestern "Railway" (reporting mark SWKR) from RailAmerica. The Union Pacific Railroad (or Union Pacific Railroad Company and simply Union Pacific) is a freight hauling railroad that operates 8,500 locomotives over 32,100 route-miles in 23 states west of Chicago and New Orleans.  The Union Pacific Railroad system is the largest in the United States and it is one of the world's largest transportation companies.  The Union Pacific Railroad is the principal operating company of the Union Pacific Corporation (); both are headquartered in Omaha, Nebraska. The Salt Lake and Utah Railroad, also known as the Orem Line or Orem Interurban, was an electric railroad which operated between downtown Salt Lake City and Payson, Utah.  Construction of the main line begun in 1913.  The railroad was financed by A. J. Orem & Company, with Walter C. Orem as president.  The railroad opened in 1914 with stops in both Utah County and Salt Lake County.  The railroad also operated a branch line which ran to Magna, Utah.  Both passenger and freight service was offered.  The line's terminus in downtown Salt Lake City was shared with the Bamberger Railroad, and was located at the current site of Abravanel Hall.  The railroad stopped service in 1946. The Las Vegas and Tonopah Railroad was a 197.9 mile railroad built by William A. Clark that ran northwest from a connection with the mainline of the San Pedro, Los Angeles and Salt Lake Railroad at Las Vegas, Nevada to the gold mines at Goldfield.  The SPLA&SL railroad later became part of the Union Pacific Railroad and serves as their mainline between Los Angeles and Salt Lake City. The Los Angeles & San Pedro Railroad was Southern California's first railroad.  Its 21 mile line from San Pedro Bay to Los Angeles was built from 1868 to 1869 and began operations on October 26, 1869.  The railroad was the brainchild of Phineas Banning and its primary purpose was to transport freight from the port to the city. The Nashville Terminal Subdivision is a railroad line owned by CSX Transportation in the U.S. State of Tennessee.  The Subdivision is broken up into 5 sections all in Nashville, Tennessee.  The northern part of the Terminal is in Madison, Tennessee at milepost 000/0BA 174 on the southern end of the Ex-L&N Mainline Subdivision at Monfort.  Disptach for the Mainline Sub is known as "LD" which is part of the Cincinnati Division.  From here in Madison begins the double track that stays for another 22 miles south to Brentwood, Tennessee.  At milepost 000/0BA/00H 176.6, the famous Johnny Cash "Amqui" location where the Ex-L&N Evansville, Indiana line, the Henderson Subdivision meets with the Terminal.  Dispatch for the Henderson Sub is known as "SA" and operates on AAR58.  There are two crossings near each other, Williams Ave and Nesbitt Lane at Amqui.  From here the Terminal goes south about 2 miles to the Nashville National Cemetery to the first major location, known as Ekin, 000179, where there is a cross over track from number 1 to number 2 track (left to right track).  There is also the first EDD (Defect Detector) at 000179.1.  Few more miles southward, the next major location appears.  At 000181.0, Maplewood is a major location for the Terminal.  From here the regular Terminal goes south to swap crews at Kayne Ave, and the right side, Radnor Cutoff, detours the city and gives yard departures and arrivals direct access to and from Radnor yard to cities like Louisville and Chicago.  The Cutoff runs from Maplewood to Shelby Park double track.  From Shebly the track converges into one to pass the historic Shelby bridge, then it opens back to double track.  From there, the cutoff hits the Intermediates at 0BA187.0 known as Chicken Pike.  The Radnor Cutoff carries the L&N mainline classification of "0BA" but meets the main at the same milepost from the Terminal.  At Chicken Pike, trains are staged to await arrival to Radnor yard.  Once they get clearance, speed is decreased to 15, and at 0BA188.1 the EDD (Defect Detector) sounds for departures and arrivals.  This location is known as North Radnor.  The right track diverging from the #2 is known as A-1, it is for departure trains to Chattanooga and Atlanta.  The left track which goes west from the #1 is known as A-2, and serves as a departure track to Memphis, and if the cutoff is out of service, all northbound departures.  The interesting piece of Maplewood is the crossovers that are there to move trains from the Cutoff to the Main.  Both lines remain double track for a while.  The main runs south for 2 more miles until the Intermediate signals at 000183.0.  Commonly trains will stop before Delmas Ave when Kayne Ave is at capacity and await dispatch permission before moving south.  From here, the main continues south until the CR Cumberland River Swingbridge, where the main converges into a single track shortly to cross the bridge.  At this point, trains had been running at track speed of around 40.  From the drawbridge into town, speed is reduced to around 10.  After the bridge is passed, the main returns to double track in downtown.  On the #1 track about a half a mile south, another connecting track is present.  This is the Wye track that connects the main with the Bruceton side, while rarely used for mainline trains, locals and river jobs use it.  The location is known as 8th Avenue or 8th Avenue Wye.  The main then runs down to Kayne Ave, the central hotbed of all Nashville thru traffic.  The Memphis, Tennessee Ex-L&N Bruceton Subdivision meets with the Terminal.  The Bruceton Sub begins at Church Street at 00N0.0.  The line then runs single track until 00N0.7 "11th Avenue" where it turns into double track and also meets the aforementioned, Wye track.  The Bruceton line then goes southwest a while to the next signals, at "Shops".  Now speed has been increased.  The line is still double track until "Sellars", where speed is increased to 40 and jurisdiction transferred to the SD Dispatcher.  For a short time, 4 main tracks are present and an additional fifth track for switchers and yard movements.  The tracks from left to right in Kayne Ave are as follows: 100, 99, 98, 12, 3.  The Kayne Ave yard is also here in this area, which houses some frieght and some switcher engines.  The tracks to the old shed are covered and removed.  The Union Station is not an active station, but a historic hotel.  Crew change usually occurs at the "walkway" which is under the Demombreun St bridge by the Kayne Ave Tower.  This is also where the Ex-NC&StL Chattanooga Subdivision begins.  Then tracks run south to Fogg St/South End where things get complicated.  At milepost 000/0BA/00J187 the 98 track merges into the 12 track, making for 3 tracks now.  There is a crossover from 99 to 12, also a crossover from 12 to 3.  About 2/10ths of a mile down the 99 merges into the 12 track reducing the tracks back to the regular double.  About 4/10ths of a mile down the line from Fogg St, 000187.4, Oak St, is a crossover track from #2 to #1 (the track names are no longer 3 and 12, but are back to regular names).  When trains use this crossover northbound, such as Memphis bound trains from the A-2 line, they refer to it as "Long Lead".  And now, the Terminal splits into two parts.  The right side turns into a single track shortly, and will become the Chattanooga Subdivision, and the left side runs south to Brentwood.  The right track runs single shortly until double track for a while.  This begins part of the Chattanooga Sub or J-Line.  The #2 meets with the A-2 connection track at 00J2.2 known as A-2.  Speed is now increased to 40.  Commonly northbounds will stage at 4th Ave on the #1 to await clearance.  Now about a mile down the #1 meets the A-1 connection line.  At 00J3.6 known as A-1.  Further down the double track ends at Glencliff (00J4.9).  Now it runs single for three miles until it hits Danley, which has the D Line connection track, which is an arrival track for incoming Radnor trains from the J Line.  At Danley, the Terminal ends but the same dispatcher handles traffic, "SC".  At Oak Street, our main terminal line goes south two miles to 000189.0 known as Criaghead or Vine Hill.  There is a crossover here from #1 to #2 track.  And there is also a connection/delivery track to the Nashville and Eastern Railroad which connects the Tennessee Central Railroad Museum to a major railroad.  Trains sometimes stop on the #2 before Craighead if they are waiting to enter Radnor yard.  Sometimes trains wait on the #1 at the Berry Road crossing if they await arrival to Kayne Ave. At this point, speed has been increased to 30 from 10.  Moving south, the line hits Radnor Yard at 000192.  The #2 track meets the E-Line arrival track which most Memphis trains and locals use.  The B-Line which meets the #1 track is used for departures out of the C yard and local jobs.  At Mayton, 000192.3, the B line meets the #1 track, and there is a crossover track from #2 to #1.  Speed is now at 40.  2 miles south, at 000194.0, South Radnor, the next intersection is present.  This is where the Radnor A yard meets the main.  There is a single departure/arrival track that meets the #2 track along with a crossover from #1 to #2 track.  Commonly, the #2 track south of the signals is used to halt trains.  This location is known as TVA, because of the power station that is adjacent.  From here the Terminal runs about 2.5 miles south until we hit the southern tip.  The tracks converge onto one single main, at 000/0BA196.6 known as Brentwood.  Speed is increased to 50 and jurisdiction to the S.E. dispatcher.  The right track is the main, S&NA North, while the left track is the Nashville Subdivision which runs to Columbia and exchanges freight with the TSRR.  The Nashville Terminal Subdivision is one of the busiest locations on the CSX network, and one of the most important. The Railroad Cottage Historic District, in Las Vegas, Nevada, was constructed by the San Pedro, Los Angeles & Salt Lake Railroad to provide housing for the railroad's workers. Gold Center was a mining town in Nye County, Nevada.  Located in the Bullfrog Mining District south of Tonapah, Gold Center was established in December 1904 with a United States Post Office being authorized on January 21, 1905.  The town began publishing its own newspaper in 1907.  The location of the town was ideal as it was on the stagecoach route to Rhyolite and Beatty.  It was also near the Amargosa River, allowing sufficient water for drinking and for two mills and an ice house.  Gold Center also sold water to Rhyolite and Carrara.  The Tonopah and Tidewater Railroad, the Las Vegas & Tonopah Railroad and the Bullfrog Goldfield Railroad all ran through Gold Center.  Gold Center also had the first brewery in the area which was built underground to maintain a cool temperature. The Denver, Northwestern and Pacific Railway was a U.S. railroad company in Colorado.  The company had numerous reorganizations throughout its financially troubled history, and later had the official names of the Denver and Salt Lake Railroad, and finally the Denver and Salt Lake Railway(reporting mark D&SL) .  By the time the company was acquired by the Denver and Rio Grande Western Railroad it was colloquially known as the Moffat Tunnel Route.  The portions still in use today are known as the Moffat Tunnel Subdivision of Union Pacific Railroad's Central Corridor.
Answer: Union Pacific Railroad