I have several wild American Elm growing on my property near Waco, Tx. I still have at least one of these potted (about 2' tall). IF someone wants it, I will send it to you bare-rooted free of charge up until end of April, except you must agree to post here annually its growth results and agree to at least weekly watering if no rainfall during spring -fall for first year. Our American Elm here appear to be DED- free, but the trees are much shorter than described back east. Our native Cedar Elm appear to be the better choice for here, but the few large American Elm growing only along river and creek beds do look nice. I am not an expert on American Elm, only an interested observer on the western fringes of their territory.

We have four species of elm common in MidTenn, American, red, winged, and September. Occasionally one will turn yellow and die, but that is not all that common. I'm not sure it is DED or one of the other maladies that afflict elms. I have planted lots of winged elms on my place, and I encourage volunteers. I like them although most consider them trash trees. I am also allowing red/Americans to volunteer. I don't know which I have, I haven't keyed them out. I once read that DED is less of a problem in warm climates, I don't have a source. Oak wilt is present here and becoming a problem, especially in the black oak group. Southern red and black oaks are particularly susceptible.

There are a number of American elm cultivars selected for DED resistance. Interesting National DED ELM trial the study in the link is interesting but doesn't cover all varieties (in fact they made a mistake with one variety), doesn't cover brand new varieties ('St. Croix'). Also doesn't cover other diseases - most notably elm yellows. There are also Asian elm varieties that are resistant to both DED and elm yellows. The interesting thing about DED is it has to have a vector (like the beetle) to get the pathogen into the tree. Sometimes DED goes through and kills a bunch of elms, but not all, even though the tree is susceptible. We still have large AE trees in MN, and they will occasionally get infected and die.

I agree with arbor Dave, that your examples bark looks like Siberian elm species. Except for leaves which almost look like Witch Elm because of unique "W" shape. Different types of elms are supposed to be able to crossbreed, so your tree might have that going for it. But Siberians suffer from cankers, and from wetwood which is normally only a visual problem. In any case regardless of living trees general health, structural wise it may never recover. Someone also suggested removal of dead wood, which I agree would be one option. We lost 80-100 old Siberian elms to extended drought few years back in our NE Illinois region. I am really a big fan of Siberian, but most produce a lot of deadwood which requires regular maintenance to remove. And at times, more dead wood caused by pruning event. Especially when vegetative management arborist contracted by utilities head back branches and limbs. I live in a community named Elmwood park, where several examples of mature public Siberian elm trees stand tilted. Which I had learned was caused by past village workers using auger to dig out hole for new tree, but drilled too deep. Then tree inevitably settled oddly. Mulberries also iconic for production of abiotic wetwood, which protects damaged tissue usually found between rubbing attachments from outside organisms trying to enter. As long as wet wood flows, oxygenless environment maintained. Ironically after our big drought, some trees were cured from wetwood production. Old sap wood can also contain stored water within American Elms, that pours out when stem severed after felling. Which is also supposed to create oxygenless environment that protects inner core of tree. Retaining pockets of accumulated rainfall in rotting out parts is also supposed to be more beneficial than drilling hole to drain it.