▁su pers eded ▁the ▁National ▁Ge od etic ▁Vert ical ▁Dat um ▁of ▁ 1 9 2 9 ▁( NG VD ▁ 2 9 ), ▁previously ▁known ▁as ▁the ▁Sea ▁Level ▁Dat um ▁of ▁ 1 9 2 9 . ▁▁ ▁N AV D ▁ 8 8 , ▁along ▁with ▁North ▁American ▁Dat um ▁of ▁ 1 9 8 3 ▁( N AD ▁ 8 3 ), ▁is ▁set ▁to ▁be ▁replaced ▁with ▁a ▁new ▁G PS - ▁and ▁grav imet ric ▁ge oid ▁model - based ▁geometric ▁reference ▁frame ▁and ▁ge op ot ential ▁dat um ▁in ▁ 2 0 2 2 . ▁ ▁Method ology ▁ ▁N AV D ▁ 8 8 ▁was ▁established ▁in ▁ 1 9 9 1 ▁by ▁the ▁minimum - constraint ▁adjust ment ▁of ▁ge od etic ▁level ing ▁observations ▁in ▁Canada , ▁the ▁United ▁States , ▁and ▁Mexico . ▁It ▁held ▁fixed ▁the ▁height ▁of ▁the ▁primary ▁t ide ▁gauge ▁benchmark ▁( sur ve ying ), ▁referenced ▁to ▁the ▁International ▁Great ▁L akes ▁Dat um ▁of ▁ 1 9 8 5 ▁local ▁mean ▁sea ▁level ▁( MS L ) ▁height ▁value , ▁at ▁R im ous ki , ▁Quebec , ▁Canada . ▁Add itional ▁tid al ▁ben ch ▁mark ▁elev ations ▁were ▁not ▁used ▁due ▁to ▁the ▁demonstrated ▁variations ▁in ▁sea ▁surface ▁top ography , ▁i . e ., ▁that ▁MS L ▁is ▁not ▁the ▁same ▁equip ot ential ▁surface ▁at ▁all ▁tid al ▁ben ch ▁marks . ▁ ▁North ▁American ▁Vert ical ▁Dat um ▁of