BASEBALL ratings are hit ting a grand-slam across the country – as the national pasttime stages a bounce-back season.

In virtually every market, baseball viewership is on the rise – with fierce rivalries igniting close races.

In New York, the heavy-hitting Yankees and pitching-savvy Mets have posted year-to-year ratings increases halfway through the season.

Both teams’ solid play has translated into viewership spikes on their respective cable homes.

This increase in local Mets/Yankees viewership mirrors a national trend as baseball reaches its midseason point with strong ratings on Fox and ESPN.

Ratings for Yankees games on the team-owned YES cable network are up 39 percent over last year.

That increase was helped by three memorable Yanks-Red Sox nailbiters (June 29-July 1) – capped by a 13-inning Yanks victory which set an all-time YES ratings record (716,000 households).

Over on the broadcast side, Yankees games on Ch. 2 have grown a modest 3 percent over last year’s season-to-date numbers.

The Mets, meanwhile, have made some ratings noise of their own as they battle for the National League East crown.

On the cable side, Mets games are up 23.8 percent on Fox Sports New York and 10.4 percent on MSG.

But biewership for Mets games on Ch. 11 is down 10 percent.