Another option if you're still on .NET framework is to use a collection initializer extension method. I add a comment when I do this and place the extension method in a separate namespace.

    // ListExtensions.cs
    internal static class
    ListExtensions
    {
        public static void Add(this List<KeyValuePair<string, int>> list, string key, int value)
        {
            list.Add(new KeyValuePair<string, int>(key, value));
        }
    }
    
    // new w/extension method
    var x = new List<KeyValuePair<string, int>>
    {
        {"a", 1},
        {"b", 2},
    };