In 1939 due to the Great Depression and trying to boost Christmas sales Thanksgiving was moved from its (at the time) usual date of the last Thursday of November to a week earlier (that year the holiday would’ve fell as late as it could on November 30 and the change made by FDR moved it up a week to the 23rd). The move encountered opposition, leading to some parts of the country observing Thanksgiving a week apart from others (and the coining of the term “Franksgiving”).
A saeculum later in 2019 another holiday may end up being observed on different dates not just throughout the country but even within a town or neighborhood. This time the holiday in question is Easter, and it would be due to action on the various denominations of Christianity rather than the government as was the case for Thanksgiving 80 years earlier. Actually, it already frequently happens that most Western churches (Catholic and Protestant) calculate Easter with a different set of rules than most Orthodox ones do (the latter uses the old method from the Julian calendar while the former ones use the more astronomically accurate Gregorian calendar rules). However, the Orthodox in the U.S. are but a small minority so there isn’t much confusion (no more so than those from other minority religions). There is a movement between the various branches of Christianity to unify the celebration of Easter though, and the most common proposal is to abandon the formulas currently in use and determine the date astronomically (using the actual full moon rather than the approximated ones currently in use and the actual vernal equinox rather than the fixed one of March 21). More specifically, under the proposal Easter would be the Sunday after the first full moon after the vernal equinox using Jerusalem meridian time for all calculations. Since the Gregorian formula is very close to astronomical reality variances for the Western churches would come only occasionally (as opposed to the Julian formula which frequently puts Easter for Orthodox churches a week later due to lunar inaccuracy and sometimes four or five weeks later due to solar inaccuracy). The next year that Western churches would see a difference with the change would be 2019, with the Easter under the current rules coming on April 21 but astronomically coming on March 24 (the difference due to the actual full moon in March coming after the equinox but the full moon under the church formula coming before March 21).
Each denomination will have to decide if and when to adopt the changes, and since there are so many Protestant denominations in the U.S. it could very well turn out in 2019 that some might have Easter on the “traditional” April 21 date while others might celebrate it on the revised date of March 24. Furthermore, jurisdictions where public holidays are scheduled around Easter (such as Good Friday and/or Easter Monday) might have some debate over which date they’re scheduled around (just like in 1939 jurisdictions had to decide whether to celebrate Thanksgiving on the “traditional” November 30 or FDR’s November 23).
Unlike the Franksgiving controversy which continued on until 1941 when the date was statutorily fixed on the fourth Thursday of November, after the spring of 2019 the Easter controversy would be moot until 2038 when there is another similar diversion due to the “full moons” coming on different sides of the (real and fixed) equinoxes (that year the current formula puts it on April 25 while astronomy puts it on March 28).
Here's some links/sources on the Thanksgiving date controversy:
Here's some on the Easter date controversy: