Groundwater-withdrawal-induced　land　subsidence　has　been　a　big　concern　in　Montgomery　County,　Texas,　U.S.　since　the　2000s.　As　of　2020,　approximately　half　of　the　entire　county　is　experiencing　subsidence　over　5　mm/year.　This　study　aims　to　investigate　ongoing　land　subsidence　in　Montgomery　County　using　groundwater-level,　extensometer,　and　GPS　datasets.　According　to　this　study,　land　subsidence　in　Montgomery　County　since　the　mid-2000s　is　primarily　contributed　by　sediment　compaction　in　the　Evangeline　and　Jasper　aquifers;　the　compaction　of　Jasper　aquifer　contributes　approximately　one-third　of　the　land　subsidence　since　the　mid-2000s;　the　pre-consolidation　heads　of　the　Chicot,　Evangeline,　and　Jasper　aquifers　in　Montgomery　County　are　close　to　each　other,　approximately　15-25　m　below　mean　sea　level;　the　virgin-compaction/head-decline　ratio　is　approximately　1:250　in　the　Evangeline　aquifer　and　1:800　in　the　Jasper　aquifer　in　central　and　southern　Montgomery　County.　As　of　2020,　the　Jasper　groundwater-level　altitude　is　approximately　20-40　m　below　the　pre-consolidation　head　in　the　central　and　southern　Montgomery　County;　the　Evangeline　groundwater-level　altitude　is　about　40-60　m　below　the　pre-consolidation　head.　Land　subsidence　will　continue　to　occur　as　long　as　the　groundwater-level　altitude　in　either　the　Evangeline　or　the　Jasper　aquifer　remains　below　the　pre-consolidation　head.