 The highway is maintained by the Texas Department of Transportation ( TxDOT ) . Part of the TxDOT 's job is to measure traffic along the highway . These counts are taken using a metric called annual average daily traffic ( AADT ) , a statistical calculation of the average daily number of vehicles that travel along a portion of the highway . The TxDOT usually measures AADT near an intersection . In 2011 , the highway 's AADT count was 1500 vehicles , taken at a point just after the intersection with SH 87 . This was an increase from the previous year , when the AADT at the same point was approximately 1400 vehicles . This was also an increase from 2009 , when the route 's AADT was just 1100 vehicles , also taken from the same point . No portion of the roadway is listed on the National Highway System , a network of roads important to the country 's economy , defense , and mobility . 
