Why is Ekadashi on a different date in the United States and India?
Because Ekadashi depends on when the sun rises where you are — and both days are correct.
Ekadashi is the eleventh tithi, a lunar day defined by the angle between the Moon and the Sun. That angle changes continuously, and the tithi begins and ends at a single moment worldwide. What differs is your sunrise.
The observance follows the day on which the Ekadashi tithi is in progress at your local sunrise. When your sunrise falls on the other side of a tithi boundary from your family's, the two of you observe on different days — both correctly.
Worked examples
New York
New York and India fall on different days for 23 of 49 Ekadashis in 2026–2027.
Edison
Edison and India fall on different days for 23 of 49 Ekadashis in 2026–2027.
Chicago
Chicago and India fall on different days for 25 of 49 Ekadashis in 2026–2027.
Houston
Houston and India fall on different days for 26 of 49 Ekadashis in 2026–2027.
Dallas
Dallas and India fall on different days for 26 of 49 Ekadashis in 2026–2027.
Atlanta
Atlanta and India fall on different days for 25 of 49 Ekadashis in 2026–2027.
San Francisco
San Francisco and India fall on different days for 28 of 49 Ekadashis in 2026–2027.
San Jose
San Jose and India fall on different days for 28 of 49 Ekadashis in 2026–2027.
Los Angeles
Los Angeles and India fall on different days for 28 of 49 Ekadashis in 2026–2027.
Seattle
Seattle and India fall on different days for 27 of 49 Ekadashis in 2026–2027.
Boston
Boston and India fall on different days for 23 of 49 Ekadashis in 2026–2027.
So who is right?
Both. This is not a disagreement between calendars; it is the same calculation applied in two places. Traditionally, you observe according to where you are.
If your family observes together across countries and you would rather match them, that is a family decision, not a calculation one — and it is a perfectly common choice.