diff --git a/packages/viewer-datagrid/src/ts/custom_elements/datagrid.ts b/packages/viewer-datagrid/src/ts/custom_elements/datagrid.ts
index 8e1597b430..7fd3d10e08 100644
--- a/packages/viewer-datagrid/src/ts/custom_elements/datagrid.ts
+++ b/packages/viewer-datagrid/src/ts/custom_elements/datagrid.ts
@@ -29,6 +29,7 @@ import { sourceColumn } from "@perspective-dev/viewer/src/ts/column-format.js";
 
 import type { View, ViewWindow } from "@perspective-dev/client";
 import type {
+    HTMLPerspectiveViewerElement,
     IPerspectiveViewerPlugin,
     PluginStaticConfig,
 } from "@perspective-dev/viewer";
@@ -73,6 +74,50 @@ export class HTMLPerspectiveViewerDatagridPluginElement
     _reset_scroll_left?: boolean;
     _reset_select?: boolean;
     _reset_column_size?: boolean;
+    _columns_config: ColumnsConfig = {};
+
+    private _persist_column_sizes = (): void => {
+        if (!this.model || this.model._config.split_by?.length > 0) {
+            return;
+        }
+
+        const columns_config = structuredClone(this._columns_config);
+        for (const column of [...this.model._column_paths, "__ROW_PATH__"]) {
+            if (columns_config[column]) {
+                delete columns_config[column].column_size_override;
+            }
+        }
+
+        const overrides = save_column_size_overrides.call(this);
+        for (const [column, width] of Object.entries(overrides)) {
+            if (width !== undefined) {
+                columns_config[column] ??= {};
+                columns_config[column].column_size_override = width;
+            }
+        }
+
+        this._columns_config = columns_config;
+        const viewer = this.parentElement as HTMLPerspectiveViewerElement;
+        void viewer?.restore?.(
+            { columns_config: JSON.parse(JSON.stringify(columns_config)) },
+            { panel: this.model._panel },
+        );
+    };
+
+    private _on_column_resize = (event: MouseEvent): void => {
+        const is_resize = event.composedPath().some((target) => {
+            return (
+                target instanceof HTMLElement &&
+                target.classList.contains("rt-column-resize")
+            );
+        });
+
+        if (is_resize) {
+            document.addEventListener("mouseup", this._persist_column_sizes, {
+                once: true,
+            });
+        }
+    };
 
     constructor() {
         super();
@@ -101,6 +146,11 @@ export class HTMLPerspectiveViewerDatagridPluginElement
     }
 
     connectedCallback(): void {
+        this.regular_table.addEventListener(
+            "mousedown",
+            this._on_column_resize,
+        );
+
         if (!this._toolbar) {
             this._toolbar = document.createElement(
                 "perspective-viewer-datagrid-toolbar",
@@ -113,6 +163,11 @@ export class HTMLPerspectiveViewerDatagridPluginElement
     }
 
     disconnectedCallback(): void {
+        this.regular_table.removeEventListener(
+            "mousedown",
+            this._on_column_resize,
+        );
+        document.removeEventListener("mouseup", this._persist_column_sizes);
         this._toolbar?.parentElement?.removeChild?.(this._toolbar);
     }
 
@@ -173,7 +228,11 @@ export class HTMLPerspectiveViewerDatagridPluginElement
         group: string | undefined,
         column_name: string,
         current_value: Record<string, unknown> | null,
-        viewer_config?: { group_by?: string[]; group_rollup_mode?: string },
+        viewer_config?: {
+            group_by?: string[];
+            split_by?: string[];
+            group_rollup_mode?: string;
+        },
         column_stats?: { abs_max: number },
     ): ColumnConfigSchema {
         return column_config_schema.call(
diff --git a/packages/viewer-datagrid/src/ts/model/column_overrides.ts b/packages/viewer-datagrid/src/ts/model/column_overrides.ts
index 69eb90dcf6..6f7f64e2cf 100644
--- a/packages/viewer-datagrid/src/ts/model/column_overrides.ts
+++ b/packages/viewer-datagrid/src/ts/model/column_overrides.ts
@@ -34,14 +34,14 @@ export function restore_column_size_overrides(
     old_sizes: ColumnOverrides,
     cache = false,
 ): void {
-    if (!this._initialized) {
-        return;
-    }
-
     if (cache) {
         this._cached_column_sizes = old_sizes;
     }
 
+    if (!this._initialized) {
+        return;
+    }
+
     const regular_table = this.regular_table as RegularTableWithOverrides;
     const overrides: Record<number, number | undefined> = {
         ...regular_table.saveColumnSizes(),
diff --git a/packages/viewer-datagrid/src/ts/plugin/column_config_schema.ts b/packages/viewer-datagrid/src/ts/plugin/column_config_schema.ts
index b0a7800a09..4c83239a6b 100644
--- a/packages/viewer-datagrid/src/ts/plugin/column_config_schema.ts
+++ b/packages/viewer-datagrid/src/ts/plugin/column_config_schema.ts
@@ -15,6 +15,7 @@ import type { ColumnConfig, DatagridPluginElement } from "../types.js";
 
 interface ViewerConfigLike {
     group_by?: string[];
+    split_by?: string[];
     group_rollup_mode?: string;
 }
 
@@ -53,6 +54,15 @@ export default function column_config_schema(
 ): ColumnConfigSchema {
     const fields: ControlSpec[] = [];
 
+    if ((viewer_config?.split_by?.length ?? 0) === 0) {
+        fields.push({
+            kind: "Number",
+            key: "column_size_override" satisfies keyof ColumnConfig,
+            default: 0,
+            min: 1,
+        });
+    }
+
     if (type === "integer" || type === "float") {
         const pos_fg = this.model!._pos_fg_color[0];
         const neg_fg = this.model!._neg_fg_color[0];
diff --git a/packages/viewer-datagrid/src/ts/plugin/draw.ts b/packages/viewer-datagrid/src/ts/plugin/draw.ts
index db486b3fb1..32a886c8b0 100644
--- a/packages/viewer-datagrid/src/ts/plugin/draw.ts
+++ b/packages/viewer-datagrid/src/ts/plugin/draw.ts
@@ -62,6 +62,9 @@ export async function draw(
 
     restore_column_size_overrides.call(this, old_sizes);
     await drawPromise;
+    if (Object.keys(old_sizes).length > 0) {
+        restore_column_size_overrides.call(this, old_sizes);
+    }
 
     this._toolbar?.classList.toggle(
         "aggregated",
diff --git a/packages/viewer-datagrid/src/ts/plugin/restore.ts b/packages/viewer-datagrid/src/ts/plugin/restore.ts
index 6379033f0d..5f77b3a520 100644
--- a/packages/viewer-datagrid/src/ts/plugin/restore.ts
+++ b/packages/viewer-datagrid/src/ts/plugin/restore.ts
@@ -27,7 +27,6 @@ import type {
 } from "../types.js";
 
 interface RestoreToken {
-    columns?: Record<string, { column_size_override?: number }>;
     edit_mode?: EditMode;
     scroll_lock?: boolean;
 }
@@ -59,15 +58,18 @@ export function restore(
     columns = JSON.parse(JSON.stringify(columns));
     const overrides: ColumnOverrides = {};
 
-    if (token.columns) {
-        for (const [col, value] of Object.entries(token.columns)) {
-            if (value.column_size_override !== undefined) {
+    for (const [col, value] of Object.entries(columns)) {
+        if (value.column_size_override !== undefined) {
+            if (!this.model?._config.split_by?.length) {
                 overrides[col] = value.column_size_override;
-                delete value["column_size_override"];
             }
+
+            delete value.column_size_override;
         }
     }
 
+    this._columns_config = structuredClone(columns);
+
     const styles: Record<string, StylesConfig> = {};
     if (columns) {
         for (const [col_name, controls] of Object.entries(columns)) {
diff --git a/packages/viewer-datagrid/src/ts/plugin/save.ts b/packages/viewer-datagrid/src/ts/plugin/save.ts
index da3cbca184..13825153e3 100644
--- a/packages/viewer-datagrid/src/ts/plugin/save.ts
+++ b/packages/viewer-datagrid/src/ts/plugin/save.ts
@@ -10,7 +10,6 @@
 // ┃ of the [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0). ┃
 // ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
 
-import { save_column_size_overrides } from "../model/column_overrides.js";
 import type { DatagridPluginElement, DatagridPluginConfig } from "../types.js";
 
 export function save(
@@ -18,23 +17,10 @@ export function save(
 ): DatagridPluginConfig | Record<string, never> {
     if (this.regular_table) {
         const token: DatagridPluginConfig = {
-            columns: {},
             scroll_lock: !!this._is_scroll_lock,
             edit_mode: this._edit_mode,
         };
 
-        const column_size_overrides = save_column_size_overrides.call(this);
-
-        for (const col of Object.keys(column_size_overrides || {})) {
-            if (!token.columns?.[col]) {
-                token.columns = token.columns || {};
-                token.columns[col] = {};
-            }
-
-            token.columns[col].column_size_override =
-                column_size_overrides[col];
-        }
-
         return JSON.parse(JSON.stringify(token));
     }
 
diff --git a/packages/viewer-datagrid/src/ts/types.ts b/packages/viewer-datagrid/src/ts/types.ts
index b4b66ab312..1276164027 100644
--- a/packages/viewer-datagrid/src/ts/types.ts
+++ b/packages/viewer-datagrid/src/ts/types.ts
@@ -198,12 +198,6 @@ export type ColumnsConfig = Record<string, ColumnConfig>;
  * `save()`/`restore()` token).
  */
 export interface DatagridPluginConfig {
-    /**
-     * Per-column state keyed by column name, e.g.
-     * `{ "Sales": { "column_size_override": 180 } }`.
-     */
-    columns?: ColumnsConfig;
-
     /** Legacy alias for `edit_mode: "EDIT"`. */
     editable?: boolean;
 
@@ -342,6 +336,7 @@ export type SortRotationOrder = Record<string, SortDir | undefined>;
 export interface DatagridPluginElement extends HTMLElement {
     regular_table: RegularTableElement;
     model?: DatagridModel;
+    _columns_config: ColumnsConfig;
     _toolbar?: DatagridToolbarElement;
     _edit_button?: HTMLElement;
     _scroll_lock?: HTMLElement;
diff --git a/packages/viewer-datagrid/test/js/column_settings.spec.ts b/packages/viewer-datagrid/test/js/column_settings.spec.ts
index 771cc6f0d7..4116b8cb8d 100644
--- a/packages/viewer-datagrid/test/js/column_settings.spec.ts
+++ b/packages/viewer-datagrid/test/js/column_settings.spec.ts
@@ -27,7 +27,7 @@ test.describe("Datagrid Column Styles", function () {
         });
     });
 
-    test.skip("Interacting with column settings does not override column width", async function ({
+    test("Interacting with column settings does not override column width", async function ({
         page,
     }) {
         const view = new PspViewer(page);
@@ -41,6 +41,14 @@ test.describe("Datagrid Column Styles", function () {
         await page.mouse.down();
         await page.mouse.move(pos!.x + 100, pos!.y + 5);
         await page.mouse.up();
+        await page.waitForFunction(async () => {
+            const viewer = document.querySelector("perspective-viewer")!;
+            const token = await viewer.save();
+            return (
+                token.columns_config?.["Row ID"]?.column_size_override !==
+                undefined
+            );
+        });
 
         const editBtn = view.dataGrid.regularTable.editBtnRow
             .locator("th.psp-menu-enabled span")
@@ -54,16 +62,64 @@ test.describe("Datagrid Column Styles", function () {
         const token = await view.save();
         test.expect(token.columns_config).toEqual({
             "Row ID": {
+                column_size_override: 150,
                 number_string_format: {
                     style: "percent",
                 },
             },
         });
-        test.expect(token.plugin_config.columns).toEqual({
-            "Row ID": {
-                column_size_override: 150,
-            },
+        test.expect(token.plugin_config.columns).toBeUndefined();
+    });
+
+    test("First restore applies and preserves column width overrides", async function ({
+        page,
+    }) {
+        const result = await page.evaluate(async () => {
+            const viewer = document.querySelector("perspective-viewer")!;
+            await viewer.restore({
+                plugin: "Datagrid",
+                columns: ["Row ID", "Sales"],
+                columns_config: {
+                    Sales: { column_size_override: 311.1875 },
+                },
+            });
+
+            const plugin = document.querySelector(
+                "perspective-viewer-datagrid",
+            ) as any;
+            const index = plugin.model._column_paths.indexOf("Sales");
+            const widths = plugin.regular_table.saveColumnSizes();
+
+            return {
+                config: (await viewer.save()).columns_config,
+                width: widths[index],
+            };
+        });
+
+        expect(result.config).toEqual({
+            Sales: { column_size_override: 311.1875 },
+        });
+        expect(result.width).toBe(311.1875);
+    });
+
+    test("Column width persistence is disabled with split-by", async function ({
+        page,
+    }) {
+        const result = await page.evaluate(async () => {
+            const viewer = document.querySelector("perspective-viewer")!;
+            await viewer.restore({
+                plugin: "Datagrid",
+                columns: ["Row ID", "Sales"],
+                split_by: ["Category"],
+                columns_config: {
+                    Sales: { column_size_override: 311.1875 },
+                },
+            });
+
+            return (await viewer.save()).columns_config?.Sales;
         });
+
+        expect(result?.column_size_override).toBeUndefined();
     });
 });