Middlemarch is named after its setting, as it takes place in Middlemarch, a fictional town in the Midlands, England, in the years 1829-32. The novel is set right when the 1832 Reform Act is being heavily debated (and this debate features heavily in the story). The 1832 Reform Act expanded the population of eligible voters in the country and changed aspects of the parliamentary system in order to make it more democratic, a progressive change that the conservative and small-minded townspeople of Middlemarch do not support.
The novel also takes place right after the Catholic Relief Act of 1829 was put into law. This Act allowed Catholics to become Members of Parliament, something that had been disallowed up until that point. (The people of Middlemarch are also overwhelmingly against this sort of reform, not including more progressive characters like Dorothea and Will.) King George IV also dies over the course of the novel, leading William IV to take power. As a leader, King William IV is much more supportive on issues related to progressive reform.
Alongside important political reforms, the early 1830s in England were also characterized by rapid developments in science, medicine, and railway development, all of which are present in the novel. As the subtitle of the book makes clear, the focus of the novel is “provincial life”—or rural living—so characters tend to be more conservative and resistant to change.