I'm not sure how to remove the line that represents the 180th meridian (international dateline) on my polygon. I have the "Russia Country Boundary 2017" feature layer added from the Living Atlas. My Projected Coordinate System is set to "Asia North Albers Equal Area Conic". I've tried to google this question, but I haven't come across an answer I can fully understand. I'm a student and very new to all this!
Using ArcGIS Pro 2.3.1
It turns out I was not projecting correctly, which was creating issues down the line when editing polygons. Here's what I did...
1. Start a blank project in ArcGIS. Insert new map, go into its properties, change the Coordinate System to "Asia North Albers Equal Area Conic".
2. Add "World Countries (Generalized)" from the Living Atlas. Select Russia and Export Features to new feature class layer.
3. Search and select the Project tool from Analysis>Geoprocessing>Tools.
4. Select the Russia layer for input. Select "Current Map" for Output Coordinate System. Run.
5.Now edit the polygons to close the gap and merge to remove any lines. All done!
The only thing that bothers me with this fix is the addition of shape area (484,914.49674 m²) and shape length (4.59 m) to the original Russia polygon. These numbers could be different depending on how you close the gap, and possibly affect data projections depending on your use of this map?