UN 13,015 (formerly UN 13,020 interpolated) near Maroon Lake and Willow Pass has been determined to be no longer a ranked summit per Lidar evaluation, which gives it 292 ft. of prominence. This has reduced the total number of ranked 13ers from 584 to 583.
From the town of Leadville, drive about 3 miles WSW on US24 to where the highway makes a sharp tunr to the south. At the intersection here, turn west onto CO300, cross the railroad tracks and drive .8 mile west to another intersection. Turn left (south) onto CR11 and drive 1.3 miles to another intersection where you will bear right, remaining on CR11 which in time will become FR110. Continue SW on the graded, gravel road for another 5 miles eventually passing the Half Moon East and West Campground and the Elbert Creek CG. About .3 mile west of the Elbert Creek CG is the trailhead for Mt. Massive, appx. 7 miles in from US24. (N 39° 09' 05.87" W 106° 25' 09.77") The Mt. Elbert TH is located just south of the entrance for the Elbert Creek CG. (N 39° 09' 08.40" W 106° 24' 43.25") If you do not have a vehicle with better clearance, you'll need to park at the trailhead. Otherwise, FR110 continues west for another 2.1 miles (or a little over 9.0 miles in from US24) to the intersection for FR110J (aka" 1103A). While these last two miles are rated 4WD, having that capability is not as important as having better clearance.
Continue driving (or hiking) west on FR110 for another .5 mile to the North Halfmoon Creek TH. FR110 beyond the turnoff for South Halfmoon Creek is definitely 4WD territory and rockier with a steep, rocky hill to climb right after the turnoff for South Halfmoon Creek. Stock 4WD should be able to handle any difficulties. At-large camping possibilities may be found in the immediate area. There is a designated parking area for the North Halfmoon Ck. trailhead, just before the main road crosses the creek. The trail for Oklahoma, the SW access to Massive and North Halfmoon Lakes begins on an old roadbed.