The United States has a long history of blocking certain Americans from voting. Voter suppression began at the founding of this nation when the right to vote in most states was limited to white male property owners. Non-whites, women, and the non-property-owning poor were excluded. 
There are three primary forms of state-sponsored voter suppression: The first makes it harder for people to register to vote. The second makes it harder for people to get to the polls. The third manipulates precinct boundaries to dilute or concentrate the vote for one party. There are also illegal voter suppression activities, like the destruction of voter registration cards.
Voter registration suppression examples include:

Stricter voter ID laws such as accepting only certain kinds of IDs, requiring certain kinds of documentation to get IDs, and requiring certain kinds of photos
Residency requirements and address requirements
Intention to stay” requirements
Restrictions on voter registration drives
Elimination of Election Day voter registration
Voter purges (when eligible voters are removed from voter rolls improperly, often without notice to voters)
Felony disenfranchisement

Voting barrier examples include:

Closing polling stations. For example, between 2012 and 2018, 8% of voting precincts in Georgia were closed and 40% of voting precincts were relocated in the state, preventing between 54,000 to 85,000 voters from voting on Election Day in 2018
Barriers related to disability
Voter intimidation tactics like armed observers at polling places
Long lines at voting places

Knowing what you now know about voter suppression:

How has voter suppression affected the current presidential election?
How has the current presidential administration use voter suppression as a means to win political tactic?
How would you counter voter suppression within your own communities?