JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maps.googleapis.com/maps/api/js?libraries=geometry,places&amp;ext=.js"></script>
<div id="map"></div>

CSS

html, body, #map {
    height: 100%;
    width: 100%;
    margin: 0px;
    padding: 0px
}

JavaScript

function initMap() {

var pos = {lat: 29.744860,lng: -95.361302};

var myOptions = {
    zoom: 11,
    center: pos,
    mapTypeId: google.maps.MapTypeId.ROADMAP
};

var map = new google.maps.Map(document.getElementById('map'), myOptions);

map.setCenter(pos);


//FIRST POLYLINE SNAP TO ROAD

roadTrip1 = [

{lat: 29.596497, lng: -95.426788},
{lat: 29.540731, lng: -95.415950},
{lat: 29.533925, lng: -95.400490},
{lat: 29.526571, lng: -95.383886},
{lat: 29.493418, lng: -95.246661},
{lat: 29.429157, lng: -95.240067},
{lat: 29.475006, lng: -94.981166},
{lat: 29.652252, lng: -95.033159},
{lat: 29.637473, lng: -95.163095},
{lat: 29.596965, lng: -95.415699}
    ];

var traceroadTrip1 = new google.maps.Polygon({
   path: roadTrip1,
                    strokeColor: '#5c6670',
                    strokeOpacity: 0.8,
                    strokeWeight: 4,
                    fillColor: '#5c6670',
                    fillOpacity: 0.25
});

var service1 = new google.maps.DirectionsService(),traceroadTrip1,snap_path=[];
traceroadTrip1.setMap(map);
for(j=0;j<roadTrip1.length-1;j++){
    service1.route({origin: roadTrip1[j],destination:
    roadTrip1[j+1],travelMode: 
    google.maps.DirectionsTravelMode.DRIVING},function(result, status) {
        if(status == google.maps.DirectionsStatus.OK) {
            snap_path = snap_path.concat(result.routes[0].overview_path);
            traceroadTrip1.setPath(snap_path);
        } else alert("directions service 1 failed:"+status)
    });
}


// SECOND POLYLINE SNAP TO ROAD
roadtrip2 = [
{lat: 29.704807, lng: -95.374714}, 
{lat: 29.753679, lng: -95.354992}, 
{lat: 29.770151, lng: -95.350105}, 
{lat: 29.813047, lng: -95.399361}, 
{lat: 29.780510, lng: -95.501962}, 
{lat: 29.731015, lng: -95.501280}, 
{lat: 29.678863, lng: -95.493037},
{lat: 29.678526, lng: -95.492811},
{lat: 29.696583, lng: -95.417439},  
{lat: 29.693119, lng: -95.413344}, 
{lat: 29.701318, lng: -95.374242}, 
{lat: 29.704807, lng: -95.374714} 
    ];

var traceroadtrip2 = new...