The vibrant landscape of the US adoption agencies industry, which has witnessed significant evolution over the years, is a testament to the changing societal values, legislative reforms, and evolving technologies. This comprehensive report unravels the intricate web of this industry’s key findings while shedding light on the prospective avenues for future growth.

At the outset, let us delve into the intriguing dynamics of the US adoption industry. It is a multifaceted network of public and private agencies, attorneys, facilitators, and other professionals. The industry is characterized by its divergent modus operandi, varying from domestic placement of infants, inter-country adoptions, foster care adoptions to adoptions involving kinship ties.

The genesis of these adoption agencies can be traced back to the mid-19th century, with the New York Children's Aid Society and the Massachusetts Infant Asylum setting the precedent. Over the decades, adoption agencies have been pivotal in shaping the adoption landscape, influenced by societal dynamics, legal mandates, and the overarching economic environment.

In terms of sheer numbers, the statistics pertaining to adoption in the US are enlightening. As per the US Department of Health and Human Services, approximately 135,000 children are adopted in the United States each year. This underscores the critical role played by adoption agencies in facilitating these processes.

A seminal aspect that warrants elaboration is the paradigm shift observed in the adoption industry's operational framework. Historically, the industry was dominated by a 'closed adoption' approach where adoptee’s ties to the biological family were severed completely. However, in the latter part of the 20th century, the pendulum swung towards the 'open adoption' practice that promotes maintaining connections with the birth family.

This transformation can be attributed to a multitude of factors, ranging from the increased rights of birth parents, the evolving societal perspectives on adoption, to the empirical evidence suggesting the psychological benefits of open adoption for the adoptee.

The legislative landscape governing the adoption industry has been a powerful determinant of its evolution. Notable regulations include the Indian Child Welfare Act (ICWA) of 1978, which safeguards the interests of Native American children, and the Multi-Ethnic Placement Act (MEPA) of 1994 that prohibits discrimination in the placement of children on the grounds of race or ethnicity.

Another legal milestone, the Hague Adoption Convention, considerably influenced international adoptions, establishing global standards to safeguard the best interests of children. The implications of such legal transformations have been far-reaching, impacting the operational nuances of adoption agencies, and shaping the adoption narratives in the society.

Drawing insights from economic theory, adoption agencies, like any other market entity, are also influenced by supply and demand dynamics. The confluence of demographic shifts, societal norms, and economic factors contribute to the creation of 'supply' (children available for adoption) and 'demand' (prospective adoptive parents). The interplay of these factors generates a complex adoption market, wherein the adoption agencies operate.

Technological advancements and digitization have also left an indelible mark on the adoption industry. Adoption agencies are increasingly leveraging technology to streamline the adoption process and facilitate matching between prospective adoptive parents and children.

The use of advanced data analytics has enabled agencies to match children with prospective families in a more efficient manner, reducing time lags. Moreover, social media platforms and online databases have revolutionized the information dissemination process, providing real-time updates and making the process more transparent and accessible.

Looking ahead, the adoption industry is poised for further transformation. Agencies would need to adapt to shifting societal norms, evolving legal mandates, and technological advancements. The adoption of technology, ensuring inclusivity, and upholding the rights of all stakeholders would be paramount for the agencies of the future.

In conclusion, the adoption agency industry in the United States is a complex yet fascinating maze of manifold stakeholders, governed by societal norms, legislative mandates, and economic forces. Its evolution is testament to the dynamism of the field, reflecting changing societal values and technological advancements. As we gaze at the horizon, the industry is set for further transformation, presenting a myriad of opportunities and challenges, shaping the adoption narratives of the future.