The hotel industry continues to see some troubled times, but the recently concluded political conventions certainly gave the lodging markets of Denver and Minneapolis welcome boosts.For the week ending Sept. 6, Minneapolis, site of the Republican Party get-together, had the biggest RevPar increase among all U.S. cities, at 143.4 percent, according to Smith Travel Research. The Democratic Convention gave Denver a similar bump, as RevPar was up substantially, by 140.8 percent, for the week ending Aug. 30. By comparison, RevPar for all U.S. hotels increased by only 1.4 percent for the week ending Aug. 30 and tumbled 6.2 percent for the week ending Sept. 6. Actually, the United States’ most high-profile convention city, Las Vegas, could have used this kind of help, as the high-flying city shows continuing signs of stress. Two major projects that would have brought a significant number of hotel rooms to the city have been delayed. The $5 billion Plaza Hotel, modeled on the New York City icon and scheduled to break ground later this year, has been postponed, with groundbreaking now scheduled for next year. That followed on the heels of Boyd Gaming’s announcement that it was ceasing construction on the massive, $4.8 billion Echelon mixed-use development project, which was slated to add approximately 5,000 hotel rooms.Gambling revenues in Nevada have fallen by nearly 2 percent for the fiscal year that ended in June, and Las Vegas’ slump may also impact the city’s ability to attract future convention business. The $890 million renovation of the Las Vegas Convention Center will now be broken into three phases, according to the Las Vegas Review-Journal. The change is likely to push back the completion date of the refurbishment beyond the original scheduled finish date of 2011.