Rails comes with a built-in rake task that allows you to check the status of migrations in the project.
$ rake db:migrate:status
database: pokemon_development
Status Migration ID Migration Name
--------------------------------------------------
up 20150219143706 Create pokemon table
down 20150228003340 Create stats table
For large projects with lots of migrations, this is going to be a lot of
output, so you can trim it down with a simple grep:
$ rake db:migrate:status | grep '^ down'
down 20150228003340 Create stats table