The Church canonizes some of her faithful as 'saints' — those who lived a Christian life more perfectly, practising charity in a 'heroic' way. This is done for two reasons. First, so they may act as exemplars for the rest of us on how to live a Christian life more perfectly, above and beyond the bare minimum. Second, the saints also act as intercessors, so that we may pray to — or more properly through them — to the Triune God, so that "Christ may be glorified in His saints" (2 Thessalonians 1:10).
Every canonized saint may also act as a 'patron' of some aspect of the Christian life, whether this be for particular places, dioceses, parishes, needs, purposes, vocations or anything else that may be required for salvation.
For more official purposes, such as for the patron of a diocese, these patrons are chosen through the Holy See — specifically the Congregation for Divine Worship and the Discipline of the Sacraments — in dialogue with the diocese and the local church. The saint decided upon is usually in accord with its people and history. For example, my own diocese of Pembroke, in eastern Ontario, was first populated by Irish immigrants; hence, the choice of Saint Columbkille, the great missionary who brought the Faith from Ireland into Scotland via the isle of Iona (a small island that was once the burial ground of kings but is today a popular Catholic retreat location).
The Holy Father may also choose patrons, such as: Our Lady of Guadalupe as patroness of the Americas, as well as the unborn; Blessed Pier Giorgio Frassati as the patron of youth; Saint Thomas Aquinas of Catholic schools and education; and so on.
Then there are the not really formally approved patrons who are adopted by custom and tradition, such as, Saint Veronica, as the patron of photographers, for the perfect 'icon' left on her veil. There is also Joseph of Cupertino, patron of test-takers, a struggling seminarian, who knew only one Scriptural passage for his final exam before ordination; and wouldn't you know, it was just the very one the bishop providentially chose!
Parents choose a patron for their children, in the name they bestow at baptism, which should laudably be the name of a saint, or at least not "foreign to Christian sentiment," and, years later, the same young people choose their own confirmation sponsor to help guide them through life. I would add the custom of adopting the saint on one's baptismal day — our spiritual birthday, along with our natural one — as fitting intercessors and exemplars. Of course, we should add our guardian angel, whose names, as Samson's parents were told, are 'mysterious,' for powerful they are indeed.
Then we may choose our own patrons saints for all that life entails, for our houses, our schools, our sports teams. Quebec, the most historically Catholic of our provinces, is filled with towns, cities, villages and streets named after saints. These are now often, ironically, decided by secular municipal councils across Canada; hence, why there are fewer saints connected to recently-named Canadian places. Although there is a back road I know of, which, by vote, was not long ago named after the Sacred Heart.
We may even choose patron saints for a particular occasion, such as: a journey; a marriage; expectant mothers (Saint Gerard!); a funeral; a hike; a get-together; or a pilgrimage. There are the popular go-to saints, such as: Anthony for lost objects; Jude for desperate causes; Peregrine for cancer patients; Joseph for the universal Church and a happy death; Our Lady, well, for just about everything!
In this fair dominion, we should develop a devotion to Saint Joseph as the patron of Canada. We should also recognize the eight Jesuit martyrs — Jean de Brébeuf and his companions — as our nation's secondary patrons. Then there is, of course, the mighty Saint Michael looking over the Archdiocese of Toronto, its cathedral and all of its apostolic work.
In this time of grace, we should adopt patron saints for all our needs, for the whole panoply of saints are waiting to hear from and intercede for us. For the kingdom of God is not far off, but all around us, in our very midst.