Combine Cells based on column value

Hi,

I have a document that has Districts in column a along with an overlapping district in Column B. So, if District 1 has 3 overlapping districts, it is in Rows 1, 2 and 3, with the corresponding value in B1, B2, B3. Then, if District 2 has 4 overlapping values, those values are in B4, B5, B6, and B7. I'd like to do some form of conditional concatenate, where I can combine all of the values into one cell for each district, separated by a ";" or some other delimiter. Is there any formula to do this


Example:
Base Overlapping District
1 Ward 1
1 Ward 2
1 Ward 3
1 Ward 4
1 Ward 5
1 Ward 6
2 Ward 5
2 Ward 6
2 Ward 7
2 Ward 8
2 Ward 9
2 Ward 10
3 Ward 9
3 Ward 11
3 Ward 12
3 Ward 13
3 Ward 14
3 Ward 15


I'd like to produce:
1 Ward 1; Ward 2; Ward 3; Ward 4; Ward 5; Ward 6
2 Ward 5; Ward 6; Ward 7; Ward 8; Ward 9; Ward 10
3 Ward 9; Ward 11; Ward 12; Ward 13; Ward 14; Ward 15


Any thoughts?

Exactly what I was looking for. Thanks so much!