História de tecnologia perdida, mas mágica manifesta

É a série Magic Time de Marc Zicree, resumo do primeiro livro :

For rising young lawyer Cal Griffin, it's just another day in the Big City -- until the lights go off ... for good. Suddenly packs of pale crouched figures are stalking the darkened subways, monsters prowl Times Square, and the people all around Cal are ... changing. Similar weirdness is happening everywhere, from the dank, cold heart of a West Virginia coal mine to a remote lab in South Dakota -- where a team of government scientists has unwittingly invited something catastrophic into the world -- to the highest levels of power in Washington, D.C. And Cal Griffin is not the only one struggling to comprehend the surreal, devouring chaos surrounding him -- nor the only one who will be forced to accept a new role in this brave new world of nightmare and wonder. For the forces bled from the stilled machines are fueling a consciousness both newly born and ancient -- and more than one unlikely hero will be needed for the titanic battle between the darkness and the light.

Parece que Chicago é mais um fator nos livros posteriores da série, como Angelfire :

In Zicree (The Twilight Zone Companion) and Bohnhoff's (The Spirit Gate) engrossing sequel to last year's Magic Time, Cal, Colleen, Goldie and Doc continue their quest for Cal's sister, Tina, a captive of the magical Source centered in Chicago. They journey from New York through a contemporary America where magic has wreaked havoc and come across the Preserve, where they recruit half-Lakota musician Enid Blindman, who can defend humans against the creations of the Source. In Chicago the company has to try freeing Enid from the Primal, the local supernatural presence, who turns out to be a golem under control of another formerly human minion of the Source. And so the quest goes on—which most readers will consider good news, as this is an intelligent variation on the quest theme as exemplified by Stephen King's The Stand. The story doesn't repeat itself; the characters grow (witness the relationship emerging between the ferocious army-brat survivalist Colleen and nurturing Chernobyl survivor Doc Lysenko); and the ultimate secret of the Source is sufficiently well hidden that several more volumes seem logically justified. The book doesn't escape the current saga-mongers' problem of losing some emotional impact for new readers, but the series will probably win a strong SF/fantasy following as long as future installments keep up the high quality.

    

Acho que você está procurando parte da antologia de livros de Terry Brook, especificamente a "Palavra e o vazio "série, e os livros de Gênesis de Shannara começando com Filhos do Armagedom .

Os principais eventos das séries Word e Void acontecem em Hopewell, Illinois, onde um demônio está tentando subverter o Nest Freemark, e é frustrado pelos Cavaleiros da Palavra (Precursors to the druids). Parte disso era a busca de um Gypsy Morph, ou encarnação da magia selvagem que sempre significa uma mudança significativa.

O primeiro livro do próximo grupo detalha o armagedon nuclear, a ascensão de criaturas mutantes e uma caminhada de volta a Hopewell para visitar o túmulo de Nest, e pegar uma mão que funciona como uma bússola. Isso leva o cavaleiro, Logan Tom, para Seattle. É aqui que também somos apresentados aos Ellcry e aos Elfos pela primeira vez, pois a magia deles está falhando e os demônios estão vazando da Proibição. Isso leva a uma migração e, posteriormente, a toda a série de Shannara.

A Palavra e o Vazio foi publicada de 1997 a 1999, com o Armageddon seguindo em 2006.