Okay, I think I found the error in the total count, and as of the 28th, 257 is correct. As best I can figure, I forgot to add Greenville, SC back onto my list when it re-opened.
Three sites have opened, making 27 for the month and 260 total: Tacoma, WA (Urb., S.R. 16 W. of I-5); Cedar City, UT (Jct. I-15/S.R. 130); Winslow, AZ (I-40, Exit 253).
Tacoma provides easier access to the Olympic Peninsula from the Seattle area and points north or east.
Cedar City shortens the 146 mile uphill leg from Mesquite to Beaver to two practical legs of 91 and 56 miles, and also provides easy access to Cedar Breaks N.M., and also makes it easier to round trip to Bryce Canyon N.P. from the southwest.
Winslow shortens the 184 mile leg between Gallup and Flagstaff to two practical legs of 128 and 56 miles.
I'll be off line from either today or tomorrow probably until Sunday, as I'm going to climb Mt. Shasta (and do Lassen as a warmup) again for the first time in 25 years or so. If anyone wants to monitor the EA map for any remaining openings in July, zoom the map all the way out so you can see all 48 contiguous states. The current count by area (area names by me), roughly from N-S and W-E is as follows:
PNW, 22
CA , 16
Northern Rockies, 12
Southern Rockies, 23
S. NM & W. TX, 2
Central, 30
Southwest Gulf, 23
Great Lakes, 33
South, 29
NE, 35
Mid-Atlantic and SE coast, 23
FL, 12
260
Note that both the number of groups, 12 as of today (I've seen anything from 9 to 13 recently), as well as which sites are included in which group may vary seemingly at random, often changing on a daily basis, which makes keeping track of individual site openings difficult. The groups only rarely correspond to state boundaries - e.g. California has 20 open sites right now, but the group I've called "CA" only has 16; the others are included in other groups.
I provide the above info as a starting point, but don't be surprised if the arrangement is completely different when you look. About all you can do if that happens is add up all the groups and get a total, to see if that's changed. If you're lucky enough that the groups (location and #) remain stable since the last time you looked and only some of the individual group totals have changed, you can look around in that group to see if there are any new site names that you don't remember and think might be new. If you post those, when I get back I can check them against my list and verify if they're new.
Sometimes I find it necessary to zoom the map in and out a few times to get a correct count, as some sites have a habit of disappearing and then reappearing for no obvious reason, which may initially lead to a total which is lower than the current one (260 as above). Usually but not always, clicking on one of the group circles to expand it, and then zooming the map all the way back out so you can see fewest number of groups again will fix the problem, but not always. You may have to repeat that a couple of times, and if that doesn't work just wait a day and try again.