diff --git a/js/app.js b/js/app.js
index a25c996..5448647 100644
--- a/js/app.js
+++ b/js/app.js
@@ -48,7 +48,6 @@ import {createSaveImageWidget} from './saveImageWidget.js'
 import GtexUtils from "./gtexUtils.js"
 import version from "./version.js"
 import {createCircularViewResizeModal} from "./circularViewResizeModal.js"
-import {convertToHubURL} from "./ucscUtils.js"
 
 document.addEventListener("DOMContentLoaded", async (event) => await main(document.getElementById('igv-app-container'), igvwebConfig))
 
@@ -84,7 +83,7 @@ async function main(container, config) {
             console.error(str)
             const googleWarning = "true" === localStorage.getItem(googleWarningFlag)
             //AlertSingleton.present(str)
-            if(!googleWarning) {
+            if (!googleWarning) {
                 localStorage.setItem(googleWarningFlag, "true")
                 alert(str)
             }
@@ -103,14 +102,11 @@ async function main(container, config) {
         try {
             const lastGenomeId = localStorage.getItem("genomeID")
             if (lastGenomeId && lastGenomeId !== igvConfig.genome) {
-                if (config.genomes.find(elem => elem.id === lastGenomeId)) {
+                if (config.genomes.find(elem => elem.id === lastGenomeId) ||
+                    ((lastGenomeId.startsWith("GCA_") || lastGenomeId.startsWith("GCF_")) && lastGenomeId.length >= 13))
+                {
                     igvConfig.genome = lastGenomeId
                     igvConfig.tracks = []
-                } else if((lastGenomeId.startsWith("GCA_") || lastGenomeId.startsWith("GCF_")) && lastGenomeId.length >= 13) {
-                    const hubURL = convertToHubURL(lastGenomeId)
-                    igvConfig.genome = {
-                        hubURL: hubURL
-                    }
                 }
             }
         } catch (e) {
@@ -131,7 +127,7 @@ async function main(container, config) {
 
         const urlSet = browser.getTrackURLs()
 
-        for (const { element, url } of urlList) {
+        for (const {element, url} of urlList) {
             if (urlSet.has(url)) {
                 element.setAttribute('disabled', true)
             } else {
@@ -242,7 +238,7 @@ async function initializationHelper(browser, container, options) {
     const trackLoader = async configurations => {
         try {
             // Add "searchable" attribute to non-indexed annotation tracks
-            for(let c of configurations) {
+            for (let c of configurations) {
 
 
             }
@@ -301,9 +297,9 @@ async function initializationHelper(browser, container, options) {
         document.querySelector('#igv-session-list-divider').style.display = 'none'
     }
 
-    createSaveImageWidget({ browser, saveModal: document.getElementById('igv-app-svg-save-modal'), imageType: 'svg' })
+    createSaveImageWidget({browser, saveModal: document.getElementById('igv-app-svg-save-modal'), imageType: 'svg'})
 
-    createSaveImageWidget({ browser, saveModal: document.getElementById('igv-app-png-save-modal'), imageType: 'png' })
+    createSaveImageWidget({browser, saveModal: document.getElementById('igv-app-png-save-modal'), imageType: 'png'})
 
     createShareWidgets(shareWidgetConfigurator(browser, container, options))
 
@@ -381,7 +377,7 @@ function createSampleInfoMenu(igvMain,
 
         localFileInput.value = ''
 
-        await trackLoadHandler([ { type: 'sampleinfo', url: paths[ 0 ] } ])
+        await trackLoadHandler([{type: 'sampleinfo', url: paths[0]}])
     })
 
     //  Dropbox
@@ -395,13 +391,14 @@ function createSampleInfoMenu(igvMain,
                 {
                     success: dbFiles => {
 
-                        const configList = dbFiles.map(( { link } ) => {
-                            return { type: 'sampleinfo', url: link }
+                        const configList = dbFiles.map(({link}) => {
+                            return {type: 'sampleinfo', url: link}
                         })
 
                         trackLoadHandler(configList)
                     },
-                    cancel: () => {},
+                    cancel: () => {
+                    },
                     linkType: "preview",
                     multiselect: false,
                     folderselect: false,
@@ -422,8 +419,8 @@ function createSampleInfoMenu(igvMain,
         googleDriveButton.addEventListener('click', () => {
 
             const filePickerHandler = async responses => {
-                const paths = responses.map(({ url }) => url)
-                await trackLoadHandler([ { type: 'sampleinfo', url: paths[ 0 ] } ])
+                const paths = responses.map(({url}) => url)
+                await trackLoadHandler([{type: 'sampleinfo', url: paths[0]}])
             }
 
             GooglePicker.createDropdownButtonPicker(false, filePickerHandler)
@@ -433,7 +430,7 @@ function createSampleInfoMenu(igvMain,
 
     // URL
     const html =
-        `<div id="${ urlModalId }" class="modal">
+        `<div id="${urlModalId}" class="modal">
 
             <div class="modal-dialog modal-lg">
     
@@ -477,17 +474,18 @@ function createSampleInfoMenu(igvMain,
             fileLoadManager: new FileLoadManager(),
             dataOnly: false,
             doURL: true
-        };
+        }
 
     const fileLoadWidget = new FileLoadWidget(fileLoadWidgetConfig)
 
     Utils.configureModal(fileLoadWidget, urlModal, async fileLoadWidget => {
         const paths = fileLoadWidget.retrievePaths()
-        await trackLoadHandler([ { type: 'sampleinfo', url: paths[ 0 ] } ])
+        await trackLoadHandler([{type: 'sampleinfo', url: paths[0]}])
         return true
     })
 
 }
+
 function configureGoogleSignInButton() {
 
     if (true === googleEnabled) {
@@ -505,7 +503,7 @@ function configureGoogleSignInButton() {
 
             if (currentUserProfile) {
                 const name = currentUserProfile.email || currentUserProfile.name || ''
-                signInOutButton.innerText = `Sign Out ${ name }`
+                signInOutButton.innerText = `Sign Out ${name}`
             } else {
                 signInOutButton.innerText = 'Sign In'
             }
@@ -656,13 +654,13 @@ async function initializeDropbox() {
     }
 }
 
-function guid  () {
-    return ("0000" + (Math.random() * Math.pow(36, 4) << 0).toString(36)).slice(-4);
+function guid() {
+    return ("0000" + (Math.random() * Math.pow(36, 4) << 0).toString(36)).slice(-4)
 }
 
 function isFile(object) {
-    if(!object) {
-        return false;
+    if (!object) {
+        return false
     }
     return typeof object !== 'function' &&
         (object instanceof File ||
diff --git a/js/genomeWidgets.js b/js/genomeWidgets.js
index de328e4..cc163ef 100644
--- a/js/genomeWidgets.js
+++ b/js/genomeWidgets.js
@@ -27,7 +27,9 @@
 import {AlertSingleton, createURLModal,EventBus,FileLoadManager,FileLoadWidget,Utils} from '../node_modules/igv-widgets/dist/igv-widgets.js'
 import Globals from "./globals.js";
 
+const MAX_CUSTOM_GENOMES = 5
 let fileLoadWidget;
+let knownGenomeIds = new Set();
 
 function createGenomeWidgets({$igvMain, urlModalId, genomeFileLoad}) {
 
@@ -59,13 +61,27 @@ function createGenomeWidgets({$igvMain, urlModalId, genomeFileLoad}) {
     });
 }
 
+/**
+ * Initialize the genome selection widget with pre-defined and user-defined genomes.  Because of the way these
+ * items are added in 'genomeDropdownLayout' they are added in reverse order.
+ *
+ * @param browser
+ * @param genomes
+ * @param $dropdown_menu
+ * @returns {Promise<void>}
+ */
 async function initializeGenomeWidgets(browser, genomes, $dropdown_menu) {
     try {
 
-        const genomeMap = await getAppLaunchGenomes(genomes);
+        // Start with predefined genomes.  This can return undefined.
+        let genomeMap = await getAppLaunchGenomes(genomes);
 
-        if (genomeMap) {
-            genomeDropdownLayout({ browser, genomeMap, $dropdown_menu });
+        // Add user loaded genomes
+        genomeMap = addCustomGenomes(genomeMap || new Map())
+
+        if(genomeMap.size > 0) {
+            genomeDropdownLayout({browser, genomeMap, $dropdown_menu});
+            knownGenomeIds = new Set(genomeMap.keys())
         }
 
     } catch (e) {
@@ -78,7 +94,6 @@ async function getAppLaunchGenomes(genomes) {
     if (undefined === genomes) {
         return undefined;
     }
-
     if (Array.isArray(genomes)) {
         return buildMap(genomes);
     } else {
@@ -98,6 +113,20 @@ async function getAppLaunchGenomes(genomes) {
     }
 }
 
+function addCustomGenomes(genomeMap) {
+    const customGenomeString = localStorage.getItem("customGenomes")
+    if(customGenomeString) {
+        const customGenomeJson = JSON.parse(customGenomeString)
+        if(customGenomeJson.length > 0) {
+            genomeMap.set('-', '-')
+            for (let json of customGenomeJson.reverse()) {
+                genomeMap.set(json.id, json)
+            }
+        }
+    }
+    return genomeMap
+}
+
 function buildMap(arrayOrJson) {
 
     const map = new Map()
@@ -118,27 +147,35 @@ function buildMap(arrayOrJson) {
 function genomeDropdownLayout({browser, genomeMap, $dropdown_menu}) {
 
     // discard all buttons preceeding the divider div
+    // TODO -- does this use of find assume there is 1 dropdown-divider?  Searching by ID would be more robust.
     let $divider = $dropdown_menu.find('.dropdown-divider');
     $divider.nextAll().remove();
 
     for (let [ key, value ] of genomeMap) {
 
-        const $button = createButton(value.name);
-        $button.insertAfter($divider);
+        if('-' === key) {
+           // Add separator
+           // TODO -- style this, <hr> is a hack
+           $('<div class="dropdown-divider"></div>').insertAfter($divider)
 
-        $button.data('id', key);
+        } else {
+            const $button = createButton(value.name);
+            $button.insertAfter($divider);
 
-        const str = `click.genome-dropdown.${ key }`;
+            $button.data('id', key);
 
-        $button.on(str, async () => {
+            const str = `click.genome-dropdown.${key}`;
 
-            const id = $button.data('id');
+            $button.on(str, async () => {
 
-            if (id !== browser.genome.id) {
-                await loadGenome(value);
-            }
+                const id = $button.data('id');
 
-        });
+                if (id !== browser.genome.id) {
+                    await loadGenome(value);
+                }
+
+            });
+        }
 
     } // for (...)
 
@@ -159,7 +196,22 @@ async function loadGenome(genomeConfiguration) {
         g = await Globals.browser.loadGenome(genomeConfiguration);
         if(g.id) {
             try {
+
+                // Last loaded genome ID, reloaded automatically on next page load
                 localStorage.setItem("genomeID", g.id)
+
+                // If this is a previously unknown genome add it to the custom list.
+                if(!knownGenomeIds.has(g.id)) {
+                    knownGenomeIds.add(g.id)
+                    const customGenomeString = localStorage.getItem("customGenomes")
+                    let customGenomeJson = customGenomeString ? JSON.parse(customGenomeString) : []
+                    customGenomeJson.unshift(g)
+                    if(customGenomeJson.length > MAX_CUSTOM_GENOMES) {
+                        customGenomeJson = customGenomeJson.slice(0,MAX_CUSTOM_GENOMES)
+                    }
+                    localStorage.setItem("customGenomes", JSON.stringify(customGenomeJson))
+                }
+
             } catch (e) {
                 console.error(e)
             }
diff --git a/js/ucscUtils.js b/js/ucscUtils.js
deleted file mode 100644
index 2b64dc1..0000000
--- a/js/ucscUtils.js
+++ /dev/null
@@ -1,17 +0,0 @@
-
-
-function convertToHubURL(accension) {
-    //https://hgdownload.soe.ucsc.edu/hubs/GCF/016/808/095/GCF_016808095.1/
-    //https://hgdownload.soe.ucsc.edu/hubs/GCA/028/534/965/GCA_028534965.1/
-    if (accension.startsWith("GCF") || accension.startsWith("GCA") && accension.length >= 13) {
-        const prefix = accension.substring(0, 3);
-        const n1 = accension.substring(4, 7);
-        const n2 = accension.substring(7, 10);
-        const n3 = accension.substring(10, 13);
-        return "https://hgdownload.soe.ucsc.edu/hubs/" + prefix + "/" + n1 + "/" + n2 + "/" + n3 + "/" + accension + "/hub.txt";
-    } else {
-        return undefined;
-    }
-}
-
-export {convertToHubURL}
\ No newline at end of file