On the surface, the most daunting task facing US envoy George Mitchell in his trip to Israel and the Palestinian territories is strengthening the Gaza cease-fire, and helping Gazans rise from the rubble.

But actually, the super diplomat's biggest challenge, as he wraps up his first trip and lays plans for future journeys, lies in coming to terms with a grim and unavoidable fact: The two-state solution is on its deathbed.

Since the Six-Day War of June 1967, the two-state solution, based on the concept of "land for peace," has been the central focus of almost all diplomatic efforts to resolve this tragedy. But because of Israel's unrelenting occupation and settlement project in the West Bank, the long-fought-for two-state solution has finally, tragically, become unworkable. Consider:

•In 1993, when Israeli Prime Minister Yitzhak Rabin and Palestine Liberation Organization leader Yasser Arafat famously shook hands on the White House lawn, there were 109,000 Israelis living in settlements across the West Bank (not including Jerusalem). Today there are 275,000, in more than 230 settlements and strategically placed "outposts" designed to cement a permanent Jewish presence on Palestinian land.

•The biggest Israeli settlement outside East Jerusalem, Ariel, is now home to nearly 20,000 settlers. Their home lies one third of the way inside the West Bank, yet the Israeli "security barrier" veers well inside the occupied territory to wrap Ariel in its embrace. The settlement's leaders proclaim confidently that they are "here to stay," and embark on frequent missions to seek new waves of American Jews to move to the settlement.

•A massive Israeli infrastructure to serve and protect the settlements – military posts, surveillance towers, and settlers-only "bypass roads" that allow Israelis easy access to prayer in Jerusalem or the seaside in Tel Aviv – has cut the West Bank into tiny pieces, fragmenting Palestinian life.

•To maintain separation between West Bank Arabs and West Bank Jews, Israel has erected more than 625 roadblocks, checkpoints, and other barriers – a 70 percent increase since 2005 in a land the size of Delaware, the second-smallest state. Israelis rarely encounter such obstacles, but Palestinians seeking to travel between villages and towns must seek permits, and even then, a short journey can take hours.

•Israel's "suburbs" in Arab East Jerusalem, home now to nearly 200,000 Jews, form a concrete ring, isolating the would-be Palestinian capital from the rest of the West Bank. It is therefore increasingly difficult to imagine how a Palestinian president would govern from a capital that is sealed off from the people of his nation.

These massive changes on the ground – the majority made since the initiation of the Oslo "peace process" – have, after 41 years, rendered the two-state solution all but impossible. Workaround "fixes"– land swaps, consolidated settlements, and networks of roads and bridges to funnel Palestinians under and around the Jewish West Bank presence – have become increasingly hard to imagine. The goal, after all, is a "viable, contiguous" Palestine, not one cut up by the visions of Israeli engineers in order to maintain an everlasting Jewish presence on Arab land.

Adding to the increasing impracticality of a two-state solution is the stubborn presence of the settlers themselves, some of whom have pledged violence should soldiers come to evict them. Their religious fervor, and their formidable numbers – dozens of times that of the Gaza settlers removed in 2005 – suggest such threats are not idle.

Israeli President Shimon Peres warned in London recently that such an "evacuation" could trigger a civil war in Israel. Weakening the two-state option even further has been the rain of Hamas rockets from Gaza, and Israel's outsized response, which have placed basic necessities and reconstruction well above peacemaking on the list of priorities.

Mr. Mitchell would do well to listen to people who are thinking beyond two-state options, and foster an openness and creativity absent from American diplomacy since the beginning of this tragedy 60 years ago.

He will continue to hear from former US negotiators, such as Aaron Miller, author of "The Much Too Promised Land," that two states represent "the least bad alternative." Indeed, some of the nightmare futures – the continuation of the status quo, which is growing inexorably into apartheid; or, expulsion of West Bank Palestinians to Jordan, which is already being seriously discussed among Israelis – are completely unacceptable. So is a one-state solution, to Israelis, which they insist would mean the end of the Jewish state.

Yet it was no less a man than Albert Einstein who believed in "sympathetic cooperation" between "the two great Semitic peoples" and who insisted that "no problem can be solved from the same level of consciousness that created it." A relative handful of Israelis and Palestinians are beginning to survey the proverbial new ground, considering what Einstein's theories would mean in practice. They might take heart from Einstein's friend Martin Buber, the great philosopher who advocated a binational state of "joint sovereignty," with "complete equality of rights between the two partners," based on "the love of their homeland that the two peoples share."

• Sandy Tolan is author of "The Lemon Tree: An Arab, A Jew, and the Heart of the Middle East." He is associate professor at the Annenberg School for Communication at the University of Southern California.