Wikipedia
Lincoln Day is the primary annual celebration and fundraising event of many state and county organizations of the Republican Party in the United States. It is held annually in February or March depending on the county and often features a well known speaker from the Republican Party.
Its counterpart for the Democratic Party, held the same time every year, is the Jefferson-Jackson Day celebration.
Though traditionally named after Abraham Lincoln as the first elected president of the Republican Party, the event has been renamed Reagan Day in some locations following the death of Ronald Reagan for the purpose of honoring Reagan and modernizing the Republican Party's message. Commenting on this difference in 2005, Senator Lindsey Graham of South Carolina joked "We don’t do Lincoln Day Dinners in South Carolina. It’s nothing personal, but it takes a while to get over things," referencing the fact that Lincoln's election led to the secession of South Carolina and other states. In some recent instances Lincoln-Reagan dinners are also held.