I hiked this trail twice over the summer: July 5, 2019 and September 29, 2019. Not sure how I managed to not have time to blog this.
Sloan Canyon National Conservation Area
largely abuts the city of Henderson. Much of the open land to the south and west of Henderson is (hopefully) permanently protected by the Conservation Area.
There are multiple official access points for hiking into the Conservation Area,
but the BLM website only directs you to one (Petroglyph Canyon).
For the rest, I had to look elsewhere. Bird and Hike
is by far the most detailed extant site I know of for hiking in the Las Vegas area.
For this trail, you access from the Shadow Canyon access point.
The free version of the All Trails app and website will also direct you to the trailhead.
It's pretty straightforward. From either I-215 (southwestern Beltway) or Saint Rose Parkway, take Eastern Avenue south. Where it splits (about two miles south of Saint Rose Parkway), stay left, on to Anthem Parkway. Two and a half miles later, turn left on Atcheley Drive. Google Maps suggests you go straight for one mile, including the .6 mile after Atcheley transitions to Somersworth Drive. After the previously-referenced one mile, turn left on Shadow Canyon Drive. Note that this will be the second time you see Shadow Canyon Drive.
If you waited until the second coming of Shadow Canyon, the trailhead will be .2 miles on your right. If you turned upon first encountering Shadow Canyon, the trailhead will be .7 miles on your left. There's a very small parking area on the east side of the road, room for maybe four cars. On-street parking is also permitted. There's water and a small shaded structure at this trailhead, but no restrooms.
From the trailhead, walk along the paved walkway towards a detention dam. You'll pass an access point to the City of Henderson's Anthem East Trail. Continue walking on the main trail, towards a small structure at the top of the dam. Attached to this structure is a BLM trail map.
For Trail 404, continue past the structure, walking along the top rim of the detention basin. About halfway along that top rim, trail sign directs you up Trail 404. (Should you pass to the other end of the rim, another trail sign also directs you up the other end of 404. However, that trail is not well-defined at the upper reaches, and I would not recommend that route.
Along the preferred route, the trail is well-marked and well-defined, except for the last section, where various use trails alternatives make their way to the top of the mountain. There is only one sign trail split this way, and you go straight to stay on Trail 404.
Volcanic rocks are you companion along this entire route. You may see rabbits, as well as lizards and insect life along the way, but it's a pretty arid route. About halfway up Black Mountain, scattered Joshua Tree begin to appear. Still pretty sparse, and none look very old. I don't know if this means they are only recently starting to grow here, or the mountain soil and environs are just too tough, so larger ones can't get enough water or can't bare the heat or cold, and die. But, what ever the reason, there are no really old, really large Joshua Tree along this route.
As you ascend Black Mountain, the panorama expands. The bright focus of several solar generating towers are visible to your south-southwest. That's Ivanpah Station, across the border, in California. You see those to the west of I-15, coming or going towards Primm.
When you get to the top, you'll also see several fields of solar panel fields, mostly to the east. U.S. 95 also shoots from left to right.
Further to the north, you may see I-11, the Boulder City Bypass, that heads from the Beltway, south of Boulder City (and separated by a large mountain), and around, to Hoover Dam. Scanning even further north brings you to Henderson and, eventually, the Las Vegas Valley. The Las Vegas Strip is somewhat west of north.
Also at the top are a roundish boulder wall, to protect you against the elements. Probably an ammo box and informal trail register will also be up there, along with an American flag, flapping in the breeze. If there's a flag there, you'll have seen it on the way up, so you'll know how much further you had to go.
The first time, up, I returned the way I came. The second time, I tried continuing a bit past the peak, because I saw a trail sign, down near the saddle to the next rise, to the north. However, following the ridge past that, I saw no additional indicators of a trail route.
The BLM map shows a "proposed" trail continuing over, then back down to the detention basin. Other sources I have read describe a trail going that way, and, as noted earlier, I did see the lower end of this trail, down at the detention basin.
But with no obvious trail to follow and not a whole lot of excess daylight, I backtracked back up to Black Mountain and returned the way I came. On a future trip, I will likely try following this alternate trail from the detention basin, to see if I can follow it up to the other end of the loop.
Bird and Hike gives the round trip distance at about 7.5 miles, with a net altitude gain of a bit under 2100 feet. There is essentially no shade on this trip, and no protection from the elements. Probably best to avoid the heat of a summer day, or especially windy times. But it's a very nice late afternoon hike, provided you are prepared to hike in the dark.