The timezone AST in the Dominican Republic

Only 1 nationwide time zone

UTC	-4
Standard time:	Atlantic Standard Time (AST)
Daylight saving time:	discontinued 1974

The Dominican Republic has an east-west extension of 3.4 degrees of longitude. Given the country's location in Caribbean, this corresponds to about 360 kilometers. With such a small extent the course of the sun at different positions in the country hardly matters. The position of the sun in the west of the country deviates from that in the east only about 14 minutes. This means the sun rises and sets 14 minutes later in the west than in the east.

The Atlantic Standard Time also applies in Anguilla, , Aruba, Barbados, in parts of Canada, in Curacao, Dominica, Grenada, Guadeloupe, Antigua and Barbuda, Caribbean Netherlands, Saint Martin, St. Martin, Martinique, Montserrat, Trinidad and Tobago, Puerto Rico, Saint Barthelemy, Saint Kitts and Nevis, Saint Lucia, Virgin Islands, Saint Vincent and the Grenadines, in parts of Greenland, on the British Virgin Islands and in the Bermudas.

No more daylight saving time in the Dominican Republic

Due to the sun's orbit around the equator, the days are longer in summer (June to September in the northern hemisphere). Countries that switch to daylight saving time in the summer months align the daylight phase with the human rhythm. Unused bright morning hours are thus shifted into the evening (more information on daylight saving time here).
Due to the relative proximity to the equator, the impact in the Dominican Republic is not particularly large. Santo Domingo is only 2,050 km from the equator. A day in midsummer would then not last from 06:03 to 19:20, but from 07:03 to 20:20. The effect would be quite noticeable in the evening, but the sun rising later in the morning falls at a time when many people are already awake. Thus, in 1974, the decision was made to finally abandon daylight saving time in the Dominican Republic.

Changes in Daylight Saving Times

In the Dominican Republic Daylight Saving Time has been observed since 1966 until 01/20/1974.