▁N AV D ▁ 8 8 ▁will ▁show ▁neg lig ible ▁change ▁from ▁one ▁dat um ▁to ▁the ▁other , ▁even ▁though ▁the ▁elev ation ▁of ▁both ▁does ▁change ▁between ▁dat ums . ▁ ▁Dat um ▁of ▁ 2 0 2 2 ▁To ▁improve ▁the ▁National ▁Sp atial ▁Reference ▁System ▁( NS RS ), ▁the ▁National ▁Ge od etic ▁Service ▁will ▁replace ▁the ▁North ▁American ▁Dat um ▁of ▁ 1 9 8 3 ▁( N AD ▁ 8 3 ) ▁and ▁the ▁North ▁American ▁Vert ical ▁Dat um ▁of ▁ 1 9 8 8 ▁( NA VD ▁ 8 8 ) ▁with ▁a ▁new ▁geometric ▁reference ▁frame ▁and ▁ge op ot ential ▁dat um ▁in ▁ 2 0 2 2 . ▁ ▁The ▁new ▁reference ▁frames ▁will ▁rely ▁primarily ▁on ▁Global ▁Navigation ▁Sat ellite ▁Systems ▁( GN SS ), ▁such ▁as ▁the ▁Global ▁Position ing ▁System ▁( G PS ), ▁as ▁well ▁as ▁on ▁a ▁grav imet ric ▁ge oid ▁model ▁resulting ▁from ▁our ▁Gra vity ▁for ▁the ▁Red ef inition ▁of ▁the ▁American ▁Vert ical ▁Dat um ▁( G RA V - D ) ▁Project . ▁ ▁These ▁new ▁reference ▁frames ▁are ▁intended ▁be ▁easier ▁to ▁access ▁and ▁to ▁maintain ▁than ▁N AD ▁ 8 3 ▁and ▁N AV D ▁ 8 8 , ▁which ▁rely ▁on ▁physical ▁survey ▁marks ▁that ▁d eter ior ate ▁over ▁time . ▁ ▁See ▁also ▁▁ ▁Alt itude ▁ ▁Ge odes y ▁ ▁Sea ▁Level ▁Dat um ▁of ▁ 1 9 2 9 ▁ ▁Top ographic