Good day, ladies and gentlemen, and welcome to The Home Depot First Quarter 2018 Earnings Conference Call. Today's call is being recorded. (Operator Instructions) At this time, I'd like to turn the conference over to Isabel Janci, Vice President of Investor Relations. Please go ahead.
Thank you Catharine, and good morning. Joining us on our call today are Craig Menear, Chairman, CEO and President; Ted Decker, Executive Vice President of Merchandising; and Carol Tome, Chief Financial Officer and Executive Vice President, Corporate Services. Following our prepared remarks, the call will be opened for questions. Questions will be limited to analyst and investors, and as a remainder, we would appreciate it, if participants will limit themselves to one question with one followup. If we are unable to get your question during the call, please call investor relations at 770-384-2387.
Before I turn the call over to Craig. Let me remind you that today's press release and the presentations made by our executives include forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. These statements are subject to risk and uncertainties and could cause actual results to differ materially from our expectations and projections. These risks and uncertainties include, but are not limited to, the factors identified in the release and in our filings with the Securities and Exchange Commission. Today's presentations will also include certain non-GAAP measures. Reconciliation of these measures is provided on our website. Now let me turn the call over to Craig.
Craig A. Menear
Thank you Isabel, and good morning everyone. Sales for the first quarter were $24.9 billion, up 4.4% from last year. Comp sales were up 4.2% from last year with US comps of positive 3.9%. Diluted earnings per share were $2.08 in the first quarter. We are pleased with our performance in the first quarter and the fundamentals of our business remains solid.
As Ted will detail, excluding weather impacted categories, our Pro and core interior project business remains strong in quarter and we saw healthy growth in maintenance and repair categories.
From a geographic perspective, weather impacts can be seen in the variability of performance across Canada, our three US divisions in 19 regions. Our largest division is the Northern division, which posted flat comps due to weakness in our season categories.The Southern and Western divisions saw relatively better weather trends and comped above the Company average. On the international front, Canada posted a slightly negative comp in local currency, while Mexico posted positive comps in local currency.
You've heard us talk about the bathtub effect based on when spring breaks, where weak seasonal sales in the first quarter are counter-balanced by strength in the second quarter. We expect that effect to be true this year. And over the past few weeks, as spring has finally arrived through the US and Canada, we are seeing strong customer demand.
Part of the strength, we saw in the business can be attributed to the health of our Pro customer, as Pro sales once again outpaced